Domain 1: Networking Concepts Flashcards

Question

What layer of the Open Systems Interconnection (OSI) model is responsible for translating and formatting information? A. Physical B. Data link C. Network D. Transport E. Session F. Presentation G. Application

Answer 1

F. Presentation The presentation layer implements functions providing formatting, translation, and presentation of information. No other layers of the OSI model translate and format application data.

Answer 2

A. Physical and data link A network interface adapter functions at the data link layer by encapsulating network layer data for transmission over the network. It provides physical layer functions by providing the connection to the network medium and generating the appropriate signals for transmission.

Answer 3

B. NDP The Neighbor Discovery Protocol (NDP) is a network layer protocol that defines five new Internet Control Message Protocol version 6 (ICMPv6) packet types, which enable IPv6 systems to locate resources on the network, such as routers and DNS servers, as well as autoconfigure and detect duplicate IPv6 addresses. Border Gateway Protocol (BGP) is an exterior gateway protocol that is designed to exchange routing information among autonomous systems. Open Shortest Path First (OSPF) is a link state routing protocol that enables routers to exchange routing table information. Power over Ethernet (PoE) is a general term for standards defining mechanisms for power delivery over Ethernet cables, along with data signals.

Answer 4

D. ISDN Integrated Services Digital Network (ISDN) is a wide area networking technology that uses the telephone infrastructure to provide a high-speed dial-up service. It is therefore not suitable for use on a PAN. Bluetooth, Z-Wave, and near-field communication (NFC) are all short-range wireless technologies that are capable of proving communications between PAN devices.

Answer 5

C. FIN The termination phase of a TCP connection begins when either the client or the server sends a message containing the FIN control bit with a value of 1. The other control bits listed have nothing to do with the connection termination procedure, and there is no END bit.

Answer 6

B. IEEE 802.11g IEEE 802.11g supports transmission speeds up to 54 Mbps, and it is backward compatible with 802.11b equipment. IEEE 802.11 cannot run at 54 Mbps, and while 802.11a can, it is not compatible with 802.11b. IEEE 802.11n cannot run at 54 Mbps, though it can run at faster speeds. Bluetooth is not compatible with any of the IEEE 802.11 standards.

Answer 7

B. IEEE 802.1Q IEEE 802.1Q is a standard that defines a mechanism (called Ethernet trunking by some manufacturers) that identifies the virtual local area network (VLAN) to which a packet belongs by inserting an extra 32-bit field into its Ethernet frame. IEEE 802.1P is a standard that defines a mechanism for implementing quality of service (QoS) at the data link layer by adding a 3-bit field into Ethernet frames. IEEE 802.1X is a standard defining an authentication mechanism called port-based network access control (PNAC). IEEE 802.1AB is a standard defining the Link Layer Discovery Protocol (LLDP).

Answer 8

C. You borrow bits from the host identifier to create a subnet identifier. You cannot extend the IP address beyond its 32-bit size, and you cannot remove bits from the network identifier, or the packets will not be routed properly. You must therefore create a subnet by borrowing bits from the host identifier.

Answer 9

C. A switch Replacing routers with switches turns an internetwork into a single large subnet, and virtual local area networks (VLANs) exist as logical elements on top of the switching fabric. Although VLANs are the functional equivalent of network layer subnets, the systems in a single VLAN are still physically connected by switches, not routers. Bridges connect network segments at the data link layer and selectively forward traffic between the segments. However, bridges do not provide a dedicated connection between two systems like a switch does, and they do not make it possible to convert a large routed internetwork into a single switched network. Therefore, they have no role in implementing VLANs. Hubs are physical layer devices that propagate all incoming traffic out through all of their ports. Replacing the routers on an internetwork with hubs would create a single shared broadcast domain with huge amounts of traffic and many collisions. Hubs, therefore, do not connect the computers in a VLAN.

Answer 10

B. Broadcast DHCP clients use broadcasts to transmit DHCPDISCOVER messages on the local network. DHCP servers are then required to respond to the broadcasts. DHCP clients cannot use unicast, multicast, or anycast messages to initiate contact with DHCP servers because they have no way of learning their addresses.

Answer 11

C. fe00::c955:c944:acdd:3fcb The address fe00::c955:c944:acdd:3fcb is correctly formatted for IPv6, with the double colon replacing three blocks of zeroes. Uncompressed, the address would appear as follows: fe00:0000:0000:0000:c955:c944:acdd:3fcb. Option A contains a nonhexadecimal digit. Option B contains only seven 16-bit blocks (and no double colon) instead of the eight required for 128 bits. Option D contains blocks larger than 16 bits.

Answer 12

C. Packets can be stored temporarily in the event of network congestion. On a packet-switched network, packets can take different routes to the destination, can be transmitted out of order, and can be routed around network congestion. The packets are then reassembled into a complete message once all of them reach the destination. Temporary message storage is an advantage of circuit switching networks.

Answer 13

A. ARP Reverse Address Resolution Protocol (RARP), Bootstrap Protocol (BOOTP), and Dynamic Host Configuration Protocol (DHCP) are all protocols that are designed to allocate IP addresses to clients. Address Resolution Protocol (ARP), on the other hand, resolves existing IP addresses into data link layer MAC (or hardware) addresses.

Answer 14

B. NAT Network Address Translation (NAT) is a service that enables computers with unregistered IP addresses to access the Internet by substituting a registered address in packets as they pass through a router. The Dynamic Host Configuration Protocol (DHCP) is an IP address allocation service. Domain Name System (DNS) resolves domain and hostnames into IP addresses, and Network Time Protocol (NTP) enables network devices to synchronize their time settings.

Answer 15

B. 4 centimeters NFC is designed to provide wireless communication between devices up to 4 cm apart, such as smartphones and payment systems.

Answer 16

C. UDP The User Datagram Protocol (UDP) provides connectionless service at the transport layer. TCP provides connection-oriented service at the transport layer. HTTP is an application layer protocol, and ARP is a data link layer protocol.

Answer 17

B. 25 A single RIP broadcast packet can include up to 25 routes. If there are more than 25 routes in the computer's routing table, then RIP must generate additional packets.

Answer 18

B. Routers Connecting subnets with routers at the network layer maintains the data link layer administrative boundaries that prevent broadcast transmissions from being propagated throughout the entire internetwork. Switching eliminates those data link layer boundaries, and administrators can use virtual local area networks (VLANs) to simulate them. Because hubs propagate all of the traffic they receive out through all of their ports indiscriminately, they create no administrative boundaries. Domains are logical groups of network devices defined by the Domain Name System (DNS). Their functions are not related to VLANs in any way. Switches are essentially multiport bridges that forward incoming traffic only to the device for which it is destined. Therefore, bridges are more closely related to eliminating administrative boundaries than to establishing them.

Answer 19

D. Resolver The client component of the Domain Name System is called the resolver. Requestor is a generic term for any system issuing requests, and only DNS servers can be authorities or forwarders.

Answer 20

D. 1 through 1023 Well-known TCP and UDP server ports fall in the range of 1 through 1023. Registered port numbers fall in the range from 1024 to 49151. Ephemeral client ports fall in the range of 49152 through 65535.

Answer 21

B. Network On a TCP/IP network, the Internet Protocol (IP) at the network layer is the protocol responsible for the delivery of data to its final destination. Data link layer protocols are only concerned with communication between devices on a local area network (LAN) or between two points connected by a wide area network (WAN). The session and application layers are not involved in the actual delivery of data.

Answer 22

C. Mesh A mesh topology is one in which every node is directly connected to every other node, therefore providing complete redundancy through the network. In a star topology, each node is connected to a central nexus, providing each with a single path to the rest of the network. In a ring topology, each node is connected to two other nodes, providing two possible paths through the network. In a bus topology, nodes are chained together in a line, providing no redundancy.

Answer 23

D. Class D Class D addresses are used for multicast transmissions. Class A, Class B, and Class C addresses are used for unicast transmissions. Class E is for experimental use only.

Answer 24

A. SAN A storage area network (SAN) is a network that is dedicated to carrying traffic between servers and storage devices. A personal area network (PAN) provides communication among devices associated with a single person, such as smartphones. A wide area network (WAN) is a network that connects devices or networks at different geographic locations. A metropolitan area network (MAN) is a type of WAN that connects devices within a limited geographic area.

Answer 25

A. Channels 1, 6, and 11 are the only three channels with frequencies that do not overlap. The 22 MHz channels in the 2.4 GHz band are spaced 5 MHz apart, which means that they overlap. Channels 1, 6, and 11 are the only three channels that are distant enough from each other not to overlap. Therefore, they do not interfere with each other. Channels 1, 6, and 11 do not differ from the other channels in their bandwidth or their transmission range. Each wireless device can be set to use only one channel. Therefore, channels 1, 6, and 11 cannot all be the default setting.

Answer 26

B. Create a new CNAME resource record. A canonical name (CNAME) resource record specifies an alternative host name (or alias) for a system already registered in the DNS. By creating a CNAME record specifying the www name, the server can be addressed using either NE6 or www. Creating an additional A resource record will cause the server to be recognized using one name or the other, but not both. Modifying the existing A record will change the hostname. PTR resource records are used only for reverse name resolution.

Answer 27

C. DNS Server Addresses The DNS Server Addresses parameter contains the addresses of servers that resolve domain names into IP addresses. Windows Internet Name Service (WINS) provides Network Basic Input/Output System (NetBIOS) name resolution. The Default Gateway parameter defines the local router to be used to access other networks. There is no such parameter as Subnet Gateway.

Answer 28

A. 255.255.224.0 The decimal value for 11111111 is 255, the value for 11100000 is 224, and the value for 00000000 is 0, so the mask is 255.255.240.0.

Answer 29

C. 49152 through 65535 Ephemeral client ports fall in the range of 49152 through 65535. Well-known TCP and UDP server ports fall in the range of 1 through 1023. Registered port numbers fall in the range from 1024 to 49151.

Answer 30

B. Class B All Class B addresses have first octet values between 128 and 191. The first octet range of a Class A address is 1 to 126, and the Class C first octet range is 192 to 223. Class D addresses have a first octet range of 224 to 239.

Answer 31

B. The port number is used by both the sender and the receiver to identify the application that generated the information in the datagram. TCP ports and UDP ports identify the application protocol or process that generated the information in a datagram. Client ports are chosen randomly from the range 1024 through 65,534. Server ports are well-known and are chosen from the range 1 through 1023.

Answer 32

B. Dynamic DNS Dynamic DNS (DDNS) is an addition to the DNS standards that eliminates the need for administrators to manually create certain DNS resource records. For example, when a DHCP server allocates an address to a client, DDNS creates a host (A) record containing the host name of the client and the newly allocated IP address. Reverse name resolution is the process of looking up host names based on IP addresses. Automatic allocation is a DHCP process by which IP addresses are permanently assigned to clients. HOSTS is a text-based name resolution method that predates DNS.

Answer 33

C. 8 The 802.11ac standard supports multiple input and multiple output (MIMO) through the use of up to eight antennae on a single device. The 802.1n standard is the only standard that supports MIMO, with up to four antennae.

Answer 34

A. Physical The physical layer of the OSI model defines the standards for the physical and mechanical characteristics of a network, such as cabling (copper and fiber), connecting hardware (hubs and switches), and signaling methods (analog and digital). All of the other layers are not involved in the mechanical characteristics of the network.

Answer 35

C. 10.1.0.253 The address 10.1.0.253 is a proper address in the private address range 10.0.0.0 to 10.255.255.255. The address 192.167.9.46 falls outside the designated private IP address range, which is 192.168.0.0 to 192.168.255.255, and is therefore not a viable address on a private network. 172.16.255.255 is a broadcast address, which you cannot assign to a host. 225.87.34.1 falls in the Class D multicast address range and cannot be assigned to a single host.

Answer 36

D. Presentation The presentation layer provides a syntax translation service that enables two computers to communicate, despite their use of different bit-encoding methods. This translation service also enables systems using compressed or encrypted data to communicate with each other.

Answer 37

C. Transport Transport layer protocols, such as Transmission Control Protocol (TCP) and User Datagram Protocol (UDP), have header fields that contain the port numbers of the applications that generated the data in the packet and that will receive it. The application, presentation, and network layers do not use port numbers.

Answer 38

D. org The topmost layer in the DNS hierarchy is represented by org, which is a top-level domain. Mydomain is a second-level domain registered by a particular organization. Paris is a subdomain within Mydomain, and www is the name of a particular host in the paris.mydomain.org domain.

Answer 39

B. 802.11ac The IEEE 802.11ac standard provides the greatest possible throughput, at up to 1.3 Gbps. The 802.11n standard runs at speeds up to 600 Mbps. The 802.11a and 802.11g standards run at up to 54 Mbps. The 802.11b standard runs at up to 11 Mbps.

Answer 40

A. Link local An IPv6 link local address is automatically assigned to each interface. Like Automatic Private IP Addressing (APIPA), it provides communication on the local network only. Global unicast addresses are routable; they are the functional equivalent of IPv4 registered addresses. Site local addresses are the equivalent of private IPv4 addresses. Anycast addresses are designed to transmit to any one host in a multicast group.

Answer 41

B. Default IP TTL The Default IP Time-to-live (TTL) option specifies the maximum number of seconds or hops allowed to an IP datagram before a router removes it from the network. This prevents datagrams from circulating endlessly. The Interface Maximum Transmission Unit (MTU) option specifies the maximum size of an IP datagram. The Address Resolution Protocol (ARP) cache timeout specifies how long entries containing the IP address assigned by the server can remain in the cache maintained by a client's ARP implementation. The Transmission Control Protocol (TCP) keepalive interval option specifies the number of seconds that the client should wait before transmitting a keepalive message over a TCP connection.

Answer 42

D. None of the above Address 127.0.0.1 is the designated IPv4 local loopback address, and as such, it is reserved. It falls between Class A, which has first octet values from 1 to 126, and Class B, which has first octet values of 128 to 191.

Answer 43

A. MIMO Multiple input and multiple output (MIMO) calls for the use of two or more antennae, enabling wireless devices to effectively multiplex signals, hereby increasing their transmission speeds. Time Division Multiple Access (TDMA) is a communication technique that splits a frequency into multiple time slots, enabling it to carry multiple data streams. A personal area network (PAN) provides communication among devices associated with a single person, such as smartphones. Ant+ is a wireless protocol that is typically used to monitor data gathered by sensors, such as those in cardiac pacemakers.

Answer 44

A. 10 subnet bits with a subnet mask of 255.255.255.192 A standard Class B address with a mask of 255.255.0.0 has 16 bits that can be used for subnets and hosts. To get 600 subnets, you must use 10 of the available bits, which gives you up to 1024 subnets. This leaves 6 host bits, which gives you up to 62 hosts per subnet, which exceeds the requirement of 55 requested by the client. Using 9 bits would give you only 510 subnets, while 11 bits would give you 2046 subnets but leave you only 5 bits for a maximum of 30 hosts, which is not enough.

Answer 45

A. ACK The receiving host uses the ACK bit to notify the sending host that it has successfully received data. The other control bits are not used to acknowledge receipt of information.

Answer 46

A. Discovery, Offer, Request, Acknowlege

Answer 47

B. Cloud bursting Cloud bursting is a common term for the offloading of excess traffic from private to public cloud resources when necessary to maintain satisfactory performance levels.

Answer 48

B. Port mirroring Port mirroring is a feature found in some switches that takes the form of a special port that runs in promiscuous mode. This means that the switch copies all incoming traffic to that port, as well as to the dedicated destination ports. By connecting an IDS or protocol analyzer to this port, an administrator can access all of the network's traffic. Stateful packet inspection is a firewall feature that enables the device to examine network and transport layer header fields, looking for patterns that indicate damaging behaviors, such as IP spoofing, SYN floods, and teardrop attacks. Trunking is a switch feature that enables administrators to create VLANs that span multiple switches. Service dependent filtering is a firewall feature that blocks traffic based on transport layer port numbers.

Answer 49

B. Private cloud In a private cloud, the same organization that utilizes the cloud services is also the sole owner of the infrastructure that provides those services. In the public cloud model, one organization functions as the provider, and another organization consumes the services of the provider. A hybrid cloud is a combination of public and private infrastructure so that the consumer organization is only a partial owner of the infrastructure. There is no such thing as an ad hoc cloud model.

Answer 50

A. Hub A hub functions only at the physical layer by forwarding all incoming signals out through all of its ports. Bridges and switches operate at the physical layer and the data link layer by selectively propagating incoming data. Routers operate at the network layer by connecting local area networks and propagating only the traffic intended for another network, based on IP addresses.

Answer 51

B. Broadcast DHCP clients use broadcasts to transmit DHCPDISCOVER messages on the local network. DHCP servers are then required to respond to the broadcasts. DHCP clients cannot use unicast, multicast, or anycast messages to initiate contact with DHCP servers because they have no way of learning their addresses.

Answer 52

B. 32 subnets and 2046 hosts With a Class B subnet mask of 255.255.248.0, the binary form of the third and fourth bytes is 11111000 00000000. There are 5 subnet bits, providing up to 32 subnets and 11 host bits, providing up to 2046 hosts.

Answer 53

A. Convergence Convergence is the term for the process by which routers propagate information from their routing tables to other routers on the network using dynamic routing protocols. Distance vectoring, redistribution, and dissemination do not describe this process.

Answer 54

D. PTR Like A and AAAA records, Pointer (PTR) records contain hostnames and IP addresses, but they are used for reverse name resolution—that is, resolving IP addresses into hostnames. A Mail Exchange (MX) record specifies the mail server that the domain should use. Canonical name (CNAME) records specify aliases for a given host name. An AAAA resource record maps a hostname to an IPv6 address for name resolution purposes.

Answer 55

C. Stable Stable is not a DHCP allocation method. DHCP supports three allocation methods: manual, dynamic, and automatic.

Answer 56

E. 16,384 The formula for calculating the number of subnets you can create using a subnet identifier of a given length is 2x, where x is the number of bits in the subnet identifier. Therefore, with a 14-bit subnet, you can conceivably create 214, or 16,384, subnets.

Answer 57

E. TCP & UDP

Answer 58

C. SaaS Software as a Service (SaaS) provides consumers with access to a specific application running on the provider's servers, in this case an email service. Consumers have control over some of their email functions, but they have no control over the operating system, the servers, or the underlying resources. The Infrastructure as a Service (IaaS) model provides the consumers with access to processing, storage, and networking resources that the consumer can use as needed. Platform as a Service (PaaS) provides consumers with the ability to install applications of their choice on a server furnished by the provider.

Answer 59

C. 00:1A:6B:31:9A:4E A media access control (MAC) address is a six-byte hexadecimal value, with the bytes separated by colons, as in 00:1A:6B:31:9A:4E. Option A, 10.124.25.43, is all decimals and uses periods; this is an IPv4 address. Option B, FF:FF:FF:FF:FF:FF, is a valid MAC address, but this value is reserved for use as a broadcast address. Option D, 03:AE:16:3H:5B:11, is not a valid hexadecimal address, which should contain only numerals and the letters A to F. Option E, fe80::89a5:9e4d:a9d0:9ed7, is too long for a MAC address; this is a valid IPv6 address.

Answer 60

D. Server Message Block (SMB) The default file sharing protocol used on all Windows operating systems is SMB. HTTP is the native protocol used by web clients and servers. NFS is the native file sharing protocol used on Unix/Linux networks. FTP is a protocol used for transferring files from one system to another. LDAP is a protocol for transmitting directory service information.

Answer 61

B. Internet Assigned Numbers Authority (IANA) The IANA assigns values for well-known port numbers. The IEEE publishes Ethernet standards, among many others. The IETF develops standards for Internet technologies. The ISO developed the Open Systems Interconnection (OSI) model.

Answer 62

A. Physical The physical layer of the OSI model defines the functions specific to the network medium and the transmission and reception of signals. All of the other layers are implemented in software and do not physically send or receive signals.

Answer 63

A. Yes, this will work. By using 4 subnet bits, it is possible for Ed to create up to 16 subnets. He can then use the remaining 4 host bits to create 14 hosts on each subnet. In this scenario, the company has a Class C Internet Protocol (IP) address, which consists of 24 network bits and 8 host bits. The company wants 10 subnets and 14 hosts per subnet, so Ed must subdivide the 8 host bits into subnet and host bits. He can allocate 4 of the 8 host bits for subnets, enabling him to create up to 16 subnets. This leaves 4 bits for host addresses, enabling Ed to create 14 hosts per subnet.

Answer 64

C. 80 Port 80 is the default well-known port for HTTP. Port 22 is for the Secure Shell (SSH) protocol, port 20 is for File Transfer Protocol (FTP), and 1720 is for the H.323 audio/video-conferencing protocol.

Answer 65

A. 67 C. 68

Answer 66

A. WAN WANs (wide area networks) connect LANs that are geographically distant. A LAN (local area network), as the name implies, is a group of computers, not other LANs, and it is contained within a small area. MANs (metropolitan area networks) connect LANs in a single metropolitan area; they are not confined to a small area. A MAN is typically larger than a LAN but smaller than a WAN. A campus area network (CAN) typically includes a group of adjacent buildings, such as those of a corporation or university.

Answer 67

C. IPAM IP address management (IPAM) is a system for planning, managing, and monitoring the IP address space for an entire enterprise network. IPAM provides links between the Dynamic Host Configuration Protocol (DHCP) and the Domain Name System (DNS) so that each is aware of the naming and addressing changes made by the other. DHCPv6 is an IPv6 version of the DHCP service, which enables it to allocate IPv6 addresses to network clients. HOSTS is a text-based name resolution method that predates DNS. Automatic Private IP Addressing (APIPA) is the mechanism that enables a DHCP client to assign itself an address when no DHCP servers are accessible.

Answer 68

B. Network NAT works by modifying IP addresses, which are a network layer element. The data link layer is concerned only with communications on the local subnet and is not involved with NAT processing. Because NAT modifies only the IP packet headers, it works with any transport layer protocol. NAT also works with most TCP/IP applications because it operates below the application layer of the OSI model.

Answer 69

C. TXT A TXT resource record contains a text string that can be used for various applications. Sender Policy Framework (SPF) inserts a list of authorized email hosts into the TXT record and DomainKey Identified Email (DKIM) inserts a public key. MX, PTR, and CNAME records are not used for SPF and DKIM. A Mail Exchange (MX) record specifies the mail server that the domain should use. Pointer (PTR) records also contain host names and IP addresses, but they are used for reverse name resolution, that is, resolving IP addresses into host names. Canonical name (CNAME) records specify aliases for a given host name.

Answer 70

A. 1.0.0.1 1.0.0.1 is a legitimate address that falls into Class A. Option B, 127.98.127.0, falls into the range of addresses reserved for use as loopback addresses (127.0.0.1 to 127.255.255.255). Option C, 234.9.76.32, falls into Class D, which is reserved for use as multicast addresses. Option D, 240.65.8.124, is a Class E address; that class is reserved for experimental use.

Answer 71

A. Diffserv Differentiated services (Diffserv) is a mechanism that provides quality of service on a network by classifying traffic types using a 6-bit value in the differentiated services (DS) field of the IP header. Class of Service (CoS) is a similar mechanism that operates at the data link layer by adding a 3-bit Priority Code Point (PCP) value to the Ethernet frame. Traffic shaping is a means of prioritizing network traffic that typically works by delaying packets at the application layer. Quality of service (QoS) is an umbrella term that encompasses a variety of network traffic prioritization mechanisms.

Answer 72

G. Application The application layer provides an entry point for applications to access the protocol stack and prepare information for transmission across a network. All other layers of the OSI model reside below this layer and rely on this entry point.

Answer 73

B. LAN A local area network (LAN), as the name implies, is a group of computers contained within a small geographic area. WANs (wide area networks) connect LANs that are geographically distant. MANs (metropolitan area networks) are not confined to a small area; they are typically larger than a LAN but smaller than a WAN. A campus area network (CAN) typically includes a group of adjacent buildings, such as those of a corporation or university.

Answer 74

D. MU-MIMO The multiple input and multiple output (MIMO) technology introduced in the IEEE 802.11n standard enables wireless devices to transmit and receive signals using multiple antennae simultaneously. The Multiuser MIMO (MU-MIMO) variant defined in the 802.11ac standard advances this technique by enabling wireless devices to transmit multiple frames to different users simultaneously, using multiple antennae. Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) is a media access control mechanism used by all 802.11 networks. Channel bonding is a wireless networking technique that combines channels to increase bandwidth.

Answer 75

C. A hybrid cloud enables administrators to migrate services between public and private resources. A hybrid cloud consists of both public and private resources. One of its main advantages is that administrators can move services from private to public cloud servers and back again as needed, depending on the current workload. Public cloud resources require authentication, so while they might be less secure than a private cloud, they are not inherently insecure. The term private cloud refers to hardware resources that are owned and operated by a single organization, regardless of their location. The various cloud delivery models do not impose specific hardware resource requirements.

Answer 76

B. Data link The only layer with a protocol (such as Ethernet) that adds both a header and a footer is the data link layer. The process of adding the headers and footers is known as data encapsulation. All other protocol layers that encapsulate data add just a header.

Answer 77

C. Network Network layer protocols specify logical addresses for end system communication and route datagrams across a network. The physical layer defines standards for physical and mechanical characteristics of a network. The data link layer uses media access control (MAC) or hardware addresses, not logical addresses. The transport layer uses port numbers, not logical addresses. Session layer protocols create and maintain a dialogue between end systems. Presentation layer protocols are responsible for the formatting, translation, and presentation of information. The application layer provides an entry point for applications to access the protocol stack and prepare information for transmission across a network.

Answer 78

F. 50134 An ephemeral port number is a temporary port supplied by a client to a server, for use during a single session or transaction. The allowed ephemeral port number values range from 49152 to 65535. The port values below 1024 are reserved for use as well-known ports, and the values from 1024 to 49151 are reserved for ports registered by specific manufacturers for their applications. Of these answers, 50134 is the only value that the client can use as an ephemeral port.

Answer 79

B. Data link The Ethernet (or IEEE 802.3) protocol at the data link layer uses MAC addresses to identify computers on the local network. Media access control (MAC) addresses are coded into the firmware of physical network interface adapters by the manufacturer. The physical layer deals with signals and is not involved in addressing. The IP protocol at the network layer has its own addressing system. The transport layer protocols are not involved in addressing

Answer 80

A. Bus The first Ethernet networks used a physical layer implementation commonly known as Thick Ethernet or 10Base5. The network used coaxial cable in a bus topology. Later Ethernet standards use twisted pair cable in a star topology. Ethernet has never used a ring or mesh topology.

Answer 81

D. FTP The File Transfer Protocol (FTP) uses two port numbers. It uses the first, port 21, for a control connection that remains open during the entire client/server session. The second port, 20, is for a data connection that opens only when the protocol is actually transferring a file between the client and the server. Network Time Protocol (NTP), Simple Network Management Protocol (SNMP), and Hypertext Transfer Protocol (HTTP) all use a single port on the server.

Answer 82

D. IMAP Internet Protocol (IP), Internet Control Message Protocol (ICMP), and Internet Group Message Protocol (IGMP) are all network layer protocols. Internet Message Access Protocol (IMAP) is a mail protocol that operates at the application layer.

Answer 83

A. Link local An IPv6 link local address is automatically assigned to each interface. Like Automatic Private IP Addressing (APIPA), it provides communication on the local network only. Global unicast addresses are routable; they are the functional equivalent of IPv4 registered addresses. Site local addresses are the equivalent of private IPv4 addresses. Anycast addresses are designed to transmit to any one host in a multicast group.

Answer 84

E. Session The session layer is responsible for creating and maintaining a dialogue between end systems. This dialogue can be a two-way alternate dialogue that requires end systems to take turns transmitting, or it can be a two-way simultaneous dialogue in which either end system can transmit at will. No other layers of the OSI model perform dialogue control between communicating end systems.

Answer 85

C. Transport layer; connection-oriented A connection-oriented transport layer protocol provides guaranteed delivery of data for upper layer applications. Connectionless protocols do not guarantee delivery of information and therefore are not a good choice. Guaranteed delivery of information is generally not a function of the data link, network, or application layer.

Answer 86

B. Presentation The presentation layer of the OSI model is responsible for translating different kinds of syntax, including text-encoding systems, such as EBCDIC and ASCII. The application, session, and physical layers do not perform this function.

Answer 87

B. 169.254.0.0 to 169.254.255.255 When a DHCP client cannot access a DHCP server, APIPA assigns it a Class B address in the range 169.254.0.0 to 169.254.255.255.

Answer 88

A. Distributed switching Distributed switching describes a hierarchical switching architecture in which remote switches (in this case departmental switches) handle most of the network traffic, with a host switch used only for traffic between the remote locations. Port forwarding is a routing method that redirects traffic intended for one IP address and port number to another. Traffic shaping is a series of techniques that optimize the allocation of network bandwidth. Neighbor discovery is an IPv6 technique used to find addresses of devices and services on the local network.

Answer 89

C. Data link layer; CSMA/CD The Ethernet protocol that handles the addressing, transmission, and reception of frames operates at the data link layer. Each frame includes hardware addresses that identify the sending and receiving systems on the local network. Ethernet uses the CSMA/CD media access control method. Physical layer specifications include the transmission of signals in the form of electrical or light pulses to represent binary code, not frames. CSMA/CA is a data link layer media access control method used by wireless LAN protocols, but not Ethernet.

Answer 90

B. Class B When a DHCP client cannot access a DHCP server, APIPA assigns it a Class B address in the range 169.254.0.0 to 169.254.255.255.

Answer 91

A. 802.11ac The IEEE 802.11ac standard, like all of the wireless LAN standards in the 802.11 working group, uses CSMA/CA for media access control. The 802.1X standard defines an authentication mechanism and does not require a media access control mechanism. The IEEE 802.3 (Ethernet) standard uses Carrier Sense Multiple Access with Collision Detection (CSMA/CD).

Answer 92

A. 10Base2 10Base2 is the physical layer specification for Thin Ethernet, which uses coaxial cable in a bus topology. 10Base-T, 100Base-TX, and 1000Base-T all use twisted pair cable in a star topology

Answer 93

D. Bus to star All coaxial-based Ethernet networks, including Thin Ethernet, use a bus topology. All UTP-based Gigabit Ethernet networks use a star topology. Therefore, an upgrade from coaxial to UTP cable must include a change in topology from bus to star.

Answer 94

A. Physical and data link layers The physical layer defines the mechanical and electrical characteristics of the cables used to build a network. The data link layer defines specific network (LAN or WAN) topologies and their characteristics. The physical layer standard that Alice will implement is dependent on the data link layer protocol she selects. The network, transport, and application layers are not concerned with cables and topologies.

Answer 95

C. 4,094 The formula for calculating the number of hosts you can create using a host identifier of a given length is 2x–2, where x is the number of bits in the host identifier. You cannot create a host with an address of all zeroes or all ones, which is why you subtract 2. On a network that uses 20 bits for network identification, 12 bits are left for the host identifier. Using those 12 bits, you can create 212–2 or 4,094 host addresses.

Answer 96

B. 192.168.2.33 to 192.168.2.46

Answer 97

C. AAAA An AAAA resource record maps a hostname to an IPv6 address for name resolution purposes. A Mail Exchange (MX) record specifies the mail server that the domain should use. Pointer (PTR) records also contain hostnames and IP addresses, but they are used for reverse name resolution—that is, resolving IP addresses into hostnames. Canonical name (CNAME) records specify aliases for a given hostname.

Answer 98

C. SSID The Service Set Identifier (SSID) is the name that you use when connecting to a wireless network. A Basic Service Set (BSS) refers to the wireless network itself, consisting of a single access point and a number of clients. An Extended Service Set (ESS) consists of two or more BSSs, using multiple access points. The Basic Service Set Identifier (BSSID) is the MAC address of the access point associated with a BSS.

Answer 99

A. MSS The Maximum Segment Size (MSS) field in the TCP Options subheader specifies the size (in bytes) of the largest segment a system can receive. The Window field indicates the amount of data (in bytes) that the receiver can accept. There are no MMS or WinMS fields in a TCP header.

Answer 100

D. QoS Quality of service (QoS) is a general term that refers to various mechanisms for prioritizing network traffic so that applications or data streams requiring a certain level of performance are not negatively affected by lower-priority transmissions. Port forwarding is a routing method that redirects traffic intended for one IP address and port number to another. Dynamic routing is a method by which routing tables are automatically updated with new information as the routing fabric of an internetwork changes. Virtual local area networks (VLANs) are a means for partitioning a broadcast domain into discrete units that are functionally equivalent to physical LANs.

Answer 101

B. Network; connectionless IP is a connectionless protocol that operates at the network layer of the OSI model. There are no connection-oriented protocols at this layer. The protocols at the transport layer include Transmission Control Protocol (TCP), which is connection-oriented, and User Datagram Protocol (UDP), which is connectionless.

Answer 102

C. Star In a logical ring topology, the signal path leads from each node to the next one, but physically, the network resembles a star, with each node connected to a central nexus. Signals travel from one node to the nexus, then to the next node, and then back to the nexus, and so on. A logical ring could not be implemented on a physical bus topology. A mesh topology could conceivably host a logical ring, but this would be highly impractical on a LAN. Ad hoc is a wireless topology that is not applicable in this situation.

Answer 103

C. IEEE 802.11n Wireless networks using equipment based on the IEEE 802.11n standard can span indoor distances of up to 175 feet at speeds up to 600 Mbps. An 802.11ac network can run at faster speeds—up to 1.3 Gbps—but it is limited to approximately 115-foot distances. Networks using 802.11g equipment can span 150 feet, but they run at only a maximum of 54 Mbps. An 802.11a network cannot span more than 75 feet, and it runs at no more than 54 Mbps.

Answer 104

C. ICMP Ping uses the Internet Control Message Protocol (ICMP) to exchange messages with other systems. ICMP is also used to return error messages to sending systems. The User Datagram Protocol (UDP) and the Transmission Control Protocol (TCP) are both transport layer protocols that carry application layer data; Ping does not use either one. The Internet Group Management Protocol (IGMP) is used to create multicast groups; Ping does not use it.

Answer 105

D. None of the above An ad hoc topology describes wireless computers that communicate directly with each other, without the need for any hardware other than their wireless network adapters. The ad hoc topology therefore does not require a router, an Internet connection, an access point, or a special antenna.

Answer 106

B. LDAP The Lightweight Directory Access Protocol (LDAP) is an application layer protocol used for managing and accessing information stored in directory services. Remote Desktop Protocol (RDP) is used to establish a graphical remote control session with another computer. Simple Network Management Protocol (SNMP) is used to carry information gathered by management agents distributed around a network to a central management server. Server Message Block (SMB) is the primary file sharing protocol used by Windows systems.

Answer 107

D. Hierarchical star Virtually all of the new Ethernet networks installed today use the star or the hierarchical star topology, with one or more switches functioning as a cabling nexus.

Answer 108

D. Three-way handshake Two systems establishing a TCP connection exchange three messages before they begin transmitting data. The exchange of these synchronization messages is referred to as a three-way handshake. The other terms listed are not formally used to describe this exchange.

Answer 109

A. Routing Information Protocol, version 1 (RIPv1) RIP v1 does not include the subnet mask in its updates. RIPv2 supports subnetting and includes the subnet mask of each network address in its updates. OSPF and BGP both include the subnet mask within their updates.

Answer 110

A. Collisions are a normal occurrence. Collisions are a normal occurrence on an Ethernet network; they occur when two nodes transmit at exactly the same time. There need not be a network fault for collisions to occur. When collisions occur, the nodes involved retransmit their packets so that no data is lost. Collisions are a phenomenon of data link layer protocols; they have nothing to do with IP addresses, which are network layer constructs.

Answer 111

C. 3 subnet bits, 5 host bits, and subnet mask 255.255.255.224 In this scenario, the last byte of the IP address assigned to the company must be subdivided into 3 subnet bits and 5 host bits. The 3 subnet bits will give Alice up to 8 subnets, with 5 host bits for up to 30 hosts per subnet. The new subnet mask is 255.255.255.224. The 224 is the decimal equivalent of the binary value 11100000, which represents the 3 subnet bits and the 5 host bits.

Answer 112

C. SaaS The Software as a Service (SaaS) model provides consumers with access to a specific application running on the provider's servers. Infrastructure as a Service (IaaS) provides the consumers with processing, storage, and networking resources that they can use to install and run operating systems and other software of their choice. Platform as a Service (PaaS) provides consumers with the ability to install applications of their choice on a server installed by the provider.

Answer 113

C. Transport Flow control is a process that adjusts the transmission rate of a protocol based on the capability of the receiver. If the receiving system becomes overwhelmed by incoming data, the sender dynamically reduces the transmission rate. In the TCP/IP protocol suite, Transmission Control Protocol (TCP) is responsible for implementing flow control. TCP runs at the transport layer. None of the other layers listed have TCP/IP protocols that provide flow control.

Answer 114

D. FE80::021F:9EFF:FEFC:7AD0 To convert a MAC address to an Extended Unique Identifier (EUI-64), you split the 6-byte MAC address into two 3-byte halves and insert the 2-byte value FFFE in between, as follows: 001F9E FFFE FC7AD0 Then, you change the seventh bit in the first byte, the universal/local bit, from 0 to 1, indicating that this is a locally created address. This results in a binary first byte value of 00000010, which converts to 02 in hexadecimal. Finally, you add the IPv6 link local prefix FE80::/10, resulting in the following complete address: FE80::021F:9EFF:FEFC: 7AD0 All of the other answers either insert the FFFE bytes in the wrong place or fail to change the universal/local bit.

Answer 115

E. International Organization for Standardization (ISO) ISO developed and published the OSI model to serve as a conceptual model for software and hardware developers. The ITU-T, formerly known as the CCITT, coordinates the development and advancement of international telecommunication networks and services. ANSI is a private organization that administers and coordinates a United States–based standardization and conformity assessment system. The IEEE publishes standards that define data link and physical layer standards. These standards are referred to collectively as the 802 series.

Answer 116

B. 255.255.240.0 The address given uses 20 bits to identify the network, leaving 12 bits for the host identifier. In binary form, therefore, the subnet mask value would be 11111111 11111111 11110000 00000000. The decimal value for 11111111 is 255, and the decimal value for 11110000 is 240. Therefore, the subnet mask is 255.255.240.0.

Answer 117

B. No, they are not on the same subnet. Ralph's subnet address is 192.168.176.160, and Ed's subnet address is 192.168.176.192. A subnet mask of 255.255.255.224 indicates that the systems are using a Class C address that has been subnetted using a 3-bit subnet identifier. When you convert the last byte of the IP addresses to binary form, you get 10101011 for Ralph's and 11000011 for Ed's. Because the first three bits (the subnet identifiers) are different, the two are on different subnets. Convert the subnet addresses 10100000 and 11000000 back to binary, and you get their respective subnet addresses: 192.168.176.160 for Ralph and 192.168.176.192 for Ed.

Answer 118

A. TCP The Transmission Control Protocol (TCP) provides connection-oriented service at the transport layer, with guaranteed delivery. The User Datagram Protocol (UDP) provides connectionless service at the transport layer. Hypertext Transfer Protocol (HTTP) operates at the application layer, and Internet Protocol (IP) is a connectionless network layer protocol.

Answer 119

D. ICMP Internet Control Message Protocol (ICMP) operates at the network layer by sending operational and error messages. It does not encapsulate upper layer protocol data. Internet Protocol (IP) operates at the network layer, but it does encapsulate transport layer protocol data. Transmission Control Protocol (TCP) and User Datagram Protocol (UDP) are transport layer protocols that encapsulate upper layer protocol data. Address Resolution Protocol (ARP) does not encapsulate upper layer protocol data, but it is a data link layer protocol.

Answer 120

C. 1022 To calculate the number of host addresses available, Alice must determine the number of host bits in the address, which is 10, raise 2 to that power, and subtract 2 for the network and broadcast addresses, which are unusable for hosts. The formula is therefore 2x–2. 210–2 = 1022.

Answer 121

C. Infrastructure An infrastructure topology uses a wireless access point (AP) to connect wireless devices to a wired network. An ad hoc topology connects wireless devices to each other, without connecting to a wired network. The star and bus topologies do not support wireless devices.

Answer 122

B. Default Gateway The Default Gateway parameter specifies the address of the local router that the end system should use to access other networks. The WINS Server Addresses and DNS Server Addresses parameters are used to resolve names to IP addresses. There is no such parameter as Subnet Gateway.

Answer 123

A. EGP An Exterior Gateway Protocol (EGP) routes datagrams between autonomous systems. An Interior Gateway Protocol (IGP) routes datagrams within an autonomous systems. Routing Information Protocol (RIP) and Open Shortest Path First (OSPF) are examples of interior gateway protocols.

Answer 124

C. 255.255.255.224 To create a network with 8 subnets and 30 hosts per subnet, Alice would have to allocate 3 of the 8 bits in the last octet for subnet identifiers. This would result in a binary value of 11100000 for the last octet in the subnet mask, which converts to a decimal value of 224.

Answer 125

B. 802.11b The IEEE 802.11b standard calls for DSSS signal modulation. All of the other standards listed call for Orthogonal Frequency-Division Multiplexing (OFDM) encoding.

Answer 126

B. Scope On a DHCP server, you create a scope that consists of a beginning and an ending IP address. Range, pool, and subnet are not technical terms for DHCP.

Answer 127

D. 160 MHz The 802.11ac standard defines the bonding of up to eight 20 MHz channels, for a total possible channel width of 160 MHz. The 802.11n standard can bond up to two channels, for a 40 MHz width. Earlier standards are limited to a single 20 MHz channel.

Answer 128

B. Data link Switches and bridges are involved in local area network (LAN) communications only and therefore operate at the data link layer.

Answer 129

A. A wireless router Most wireless routers are designed to provide connecting workstations with IP addresses and other TCP/IP configuration parameters. Switches and bridges are data link layer devices and hubs are physical layer devices, none of which are capable providing clients with network layer IP addresses.

Answer 130

E. Application, presentation, session, transport, network, data link, physical The correct order of the OSI model layers, from top to bottom, is application, presentation, session, transport, network, data link, physical.

Answer 131

A. HTTP The Hypertext Transfer Protocol (HTTP) is the primary protocol used for web client/server communications. Hypertext Markup Language is a coding language used to create web content. Simple Mail Transfer Protocol (SMTP) and File Transfer Protocol (FTP) can both be used in web communications, but neither is the primary protocol.

Answer 132

B. SCP C. SFTP G. SSH

Answer 133

A. The DNS server responds immediately to the query with the best information it has in its resource records or in its cache or, failing that, with an error message stating that it could not resolve the requested name. When a DNS server receives an iterative query, it responds immediately with the best information that it has available or with an error message. It does not send queries to other servers.

Answer 134

A. IaaS The Infrastructure as a Service (IaaS) model provides the consumers with the most control, as the provider furnishes processing, storage, and networking resources that the consumer can use as needed. Platform as a Service (PaaS) provides consumers with the ability to install applications of their choice on a server furnished by the provider, but they have only limited control over the server and no control over the underlying resources. Software as a Service (SaaS) provides consumers with access to a specific application running on the provider's servers, but the consumers have no control over the operating system, the servers, or the underlying resources.

Answer 135

C. A computer with two sets of networking protocols A dual stack is an IP implementation that includes both IPv4 and IPv6 protocol stacks, operating simultaneously. A computer with two network adapters or connections to two network segments is often called multihomed. A computer with two installed operating systems is called a dual-boot system.

Answer 136

D. Transport There are two types of transport layer protocols: connection-oriented and connectionless. Connection-oriented protocols guarantee the delivery of data from source to destination by creating a connection between the sender and the receiver before any data is transmitted. Connectionless protocols do not require a connection between end systems in order to pass data. The physical layer does not use connectionless or connection-oriented protocols; it defines standards for transmitting and receiving information over a network. The data link layer provides physical addressing and final packaging of data for transmission. The network layer is responsible for logical addressing and routing. The session layer is responsible for creating and maintaining a dialogue between end systems. The presentation layer is responsible for the formatting, translation, and presentation of information. The application layer provides an entry point for applications to access the protocol stack and prepare information for transmission across a network.

Answer 137

A. Bus A cable break in a bus topology would split the network into two halves, preventing the nodes on one side of the break from communicating with those on the other. In addition, both halves of the network would be left with one unterminated end, which would prevent the computers on each side of the break from communicating effectively. A cable break in a star or logical ring topology would only interrupt the connection of a single computer to the network. The mesh topology is not often used for LANs, but redundant network connections are a characteristic of mesh networks, which means that a single cable break would have no effect on the network at all.

Answer 138

C. 1.3 Gbps The 802.11ac standard defines a wireless LAN running at a speed of up to 1.3 gigabits per second (Gbps). None of the other 802.11 standards call for speeds beyond 600 Mbps. No currently ratified standard enables speeds of 2.6 Gbps.

Answer 139

D. Link state protocol Distance vector protocols rely on hop counts to evaluate the efficiency of routes. Link state protocols use a different type of calculation, usually based on Dijkstra's algorithm. The terms interior gateway protocol and edge gateway protocol do not refer to the method of calculating routing efficiency.

Answer 140

D. Infrastructure A wireless access point is a device with a wireless transceiver that also connects to a standard cabled network. Wireless computers communicate with the access point, which forwards their transmissions over the network cable. This is called an infrastructure topology. A star or bus network requires the computers to be physically connected to the network cable, and an ad hoc topology is one in which wireless computers communicate directly with one another.

Answer 141

A. VLSM Variable-length subnet masking (VLSM) describes the process of subnetting a network address by assigning an arbitrary number of host bits as subnet bits, providing administrators with great flexibility over the number of subnets created and the number of hosts in each subnet. Automatic Private IP Addressing (APIPA) is the process by which a DHCP client assigns itself an IP address when no DHCP servers are accessible. Virtual local area networks (VLANs) are logical structures used to create separate broadcast domains on a large, switched network. Extended Unique Identifier-64 (EUI-64) is an addressing method used to create IPv6 link local addresses out of media access control (MAC) addresses.

Answer 142

B. PaaS The Platform as a Service (PaaS) model provides consumers with the ability to install applications of their choice on a server furnished by the provider. Infrastructure as a Service (IaaS) provides the consumers with processing, storage, and networking resources that they can use to install and run operating systems and other software of their choice. Software as a Service (SaaS) provides consumers with access to a specific application running on the provider's servers.