Client Server 1 Flashcards
(105 cards)
1
Q
collection of individual networks, connected by intermediate networking devices, that functions as a single large network.
A
intranetwork
2
Q
evolved around the PC revolution.
A
LAN
3
Q
interconnect LANs with geographically dispersed users to create connectivity
A
WAN
4
Q
Physical Network Components
A
- router
- cable
- switching equipments
- transport stack
5
Q
Transport Stack examples
A
- TCP/IP
- NetBIOS
- IPX
- DECNet
- AppleTalk
- APPC
6
Q
conceptual framework which breaks down the complexity of networking into seven layers
A
OSI
7
Q
OSI 7 layers
A
- Application
- Presentation
- Session
- Network
- Data Link
- Physical
- Transport
8
Q
deal with application issues and generally are implemented only in software
A
upper layer
9
Q
handle data transport issues.
A
lower layer
10
Q
Concerned with the physical, mechanical and electrical characteristics of the network hardware – cables, voltages, etc
A
physical layer
11
Q
Concerned with the error-free delivery of data
A
Data Link Layer
12
Q
Organizes raw bit stream into groupings of bits
A
frames
13
Q
Transfers frames between devices on a single network
A
Data Link Layer
14
Q
The Institute of Electrical and Electronics Engineers (IEEE) has subdivided the data link layer into two sublayers
A
Logical Link Control (LLC) and
Media Access Control (MAC).
14
Q
Organizes raw bit stream into groupings of bits, called frames
A
Data Link Layer
15
Q
sub-layer defines the relationship at the hardware level between Physical Layer devices, like Network Adapter Cards, and the Data Link Layer
A
Media Access Control
16
Q
sub-layer defines the relationship between the MAC sub-layer and Data Link Layer devices and drivers
A
Logical Link Layer
17
Q
Handles routing between networks and timely delivery of data
A
Network Layer
18
Q
Packets include a header which includes network addresses for the source and destination
A
Network Layer
19
Q
Organizes frames from the Data Link Layer into packets
A
Network Layer
20
Q
Responsible for delivering data reliably
A
Transport Layer
21
Q
Transport Layer Operations (4)
A
- Building up and tearing down connections
- packet sequencing
- acknowledgements
- flow control
22
Q
Provides mechanisms to establish and maintain communications between applications.
A
session layer
23
Q
session layer operations
A
- Access authentication (for example, logging into a server)
- Session Management
- Verification that adequate disk space is available for a request
- Notifying a user that a printer is offline
24
Responsible for formatting, representing and translating data
presentation layer
25
presentation layer operations
* ASCII to EBCDIC translation
* Compression of data
* Encryption of data
26
Provides interface between the network and the application software
Application Layer
27
Umbrella committee
IEEE 802.1
28
Umbrella committee
IEEE 802.2
29
Defines Ethernet and its variations, including 10Base5, 10Base2, 10BaseT and 100BaseT
IEEE 802.3
30
Defines Token Ring
IEEE 802.5
31
Provides the physical and electrical connection required to access the network cabling.
physical layer
32
Provides the processing to assemble or disassemble the bit stream on the cable into frames suitable for the Media Access Method* in use
data link layer
33
* Operates at the Physical and Data Link Layers of the ISO Reference Model
* Media-dependent (physical connector)
* Media Access Method-dependent (Ethernet vs Token Ring, etc.)
* Protocol-independent (i.e. an Ethernet NIC can simultaneously connect to a LAN server running IPX/SPX and to a UNIX host running TCP/IP)
Network Interface Card (NIC)
34
* Amplifies and rebroadcasts a signal
* Extends the distance a signal may be run reliably over a cable
* Makes no decisions based on signal content
repeater
35
* Used as a concentrator to join multiple workstations with a single link to the rest of the LAN
* Functions as a multi-port repeater
* Signals received on any port are immediately retransmitted to all other ports on the hub.
* Increases the number of connectable devices
* Operates at the OSI Physical Layer (Level 1)
hub
* Personal hub
* Stack hubs
36
* Looks at destination address of a frame and internally establishes a logical connection with the port connected to the destination node.
* Other ports on the switch have no part in the connection
* Result: Each port on the switch corresponds to an individual collision domain, and network collision is avoided.
* Operates at the OSI Data Link Layer (Level 2)
* Essentially an intelligent hub
switch
37
* Operate at the Data Link layer
* Establish logical connections between ports based on MAC addresses
* Used to segment existing network into small collision domains
Layer 2 switch based on bridging technology
38
* Used to divide a network into mutually isolated segments
* Operates at the Data Link Layer (layer 2) of the ISO Reference Model
* Physical media-dependent; usually media access layer dependent
* Protocol-independent above the Data Link Layer
bridge
39
* Operate at the Network Layer
* Establish logical connections between ports based on network addresses
* Used to connect different networks into an internetwork
Layer-3 (based on routing technologies) (aka routing or multilayer switches)
40
* Used to connect one network to another
* Operates at the Network Layer (layer 3) of the ISO Reference Model
* Media-independent
* Protocol-dependent above the Data Link Layer
* Works with packets and their logical addresses
router
41
* Some protocols (e.g. TCP/IP, IPX/SPX) have packets that include the Network Layer logical addresses needed by routers
* Others (e.g. NetBEUI) do not, and are non-routed/non-routable protocols
Routed/Routable protocols
42
* Used to translate between incompatible protocols
* Can function at any one layer of the ISO Reference Model, or at at several layers simultaneously.
* Most commonly used at Session Layer (layer 5) and above
gateway
43
* acts as an intermediary for certain protocol exchanges.
* Operates at the Application Layer (layer 7)
proxy server
44
The most common use for a proxy server
HTTP proxy
45
Can prevent access to certain web sites, such as pornographic sites, or a company's competitors' sites.
Firewalling and Filtering
46
* The network can be configured so that the HTTP proxy server is the only machine that is directly connected to the Internet.
* This can improve network bandwidth, and thus performance
Connection Sharing
47
* If many users access certain sites often, an HTTP proxy server can cache those web sites' pages/images/etc. in its own local storage, and thus avoid unnecessary Internet access.
* This can improve network bandwidth, and response times
caching
48
There are three reasons to employ a proxy server
1. firewalling and filtering
2. connection sharing
3. caching
49
Data is transmitted over a network using
packets
50
block of user data together with necessary address and administration information attached, to allow the network to deliver the data to the correct destination.
packet
51
which contains the information needed to get the packet from the source to the destination
header
52
which contains the information to be transmitted
data area
53
* a self-contained packet, which:
* Contains enough information in the header to allow the network to forward it to the destination, independently of previous or future datagrams.
* Requires no setup before a computer tries to send datagrams to a computer with which it has not previously communicated
datagram
54
distinguish the packet from "dead air"
delimiters
55
detect errors
checksums
56
address and control
fields specific to the link
57
multiplexer divides the underlying communication channel so that it can be used simultaneously for more than one transmission.
frame
58
* Messages that are sent from one device to another device
* Not intended for others
* A "private conversation" (but eavesdropping is still possible).
unicast messages
59
* Messages sent to every device on a network.
* "Making an announcement"
broadcast messages
60
* Messages sent to a group of stations that meet a particular set of criteria
* These stations are usually related to each other in some way, such as serving a common function, or being set up into a particular multicast group
* A "small discussion group"
multicast messages
61
the specification of a set of rules for a particular type of communication.
network protocol
62
to divide the protocol design into a number of smaller parts, each of which accomplishes a particular sub-task.
Protocols are layered
63
Common network protocols include
* TCP, IP, UDP, ICMP (Internet Control Message Protocol)
* FTP, Telnet, SMTP, DNS, HTTP, POP3, NNTP, NetBIOS, IRC, SSH.
64
application layer example
* HTTP
* SMTP
* FTP
* SSH
* IRC
65
transport layer
* TCP
* UPD
* DCCP
* ICMP
* RTP
66
Network layer
* IPv4
* IPv6
* ARP
67
Data link layer
* Ethernet
* Wifi
* Token Ring
68
a data-oriented protocol used by source and destination hosts for communicating data across a packet-switched internetwork.
IP
69
allows programs on networked computers to create connections to one another, over which they can send data.
TCP
70
* A connectionless protocol.
* A minimal message-oriented transport layer protocol
* Provides a very simple interface between a network layer below and an application layer above.
* Provides no guarantees for message delivery and a UDP sender retains no state on UDP messages once sent onto the network.
UDP
71
Examples of applications that often use UDP include
1. Streaming media
1. Real-time multi-player games
1. Voice over IP (VoIP)
1. DNS (Domain Name System)
1. SNMP (Simple Network Management Protocol)
1. DHCP (Dynamic Host Configuration Protocol)
1. RIP (Routing Information Protocol
1. General message broadcasting or multicasting
72
* An extension of IP; a Network Layer (Layer 3) protocol
* Supports packets containing error, informational, and control messages
ICMP
73
is a standard for securing IP communications by encrypting and authenticating all IP packets. Operates at the Network Layer (layer 3) of the OSI model.
IPSec (IP Security)
74
IPSec 3 major protocols
* Internet Security Association and Key Management Protocol (ISAKMP)
* Authentication Header (AH)
* Encapsulating Security Payload (ESP)
75
used for creating and maintaining Security Associations (SAs)
ISKAMP
76
adds information to the header of a packet the for purpose of integrity and authentication.
Authentication Header (AH)
77
adds guarantees of confidentiality by means of encryption.
Encapsulating Security Payload (ESP)
78
ESP supports two different modes of operation
1. Transport Mode
2. Tunnel Mode
79
* Creates virtual circuits between two networking devices, and encrypts all the data passed between them.
* Encrypts the packet header, as well as the payload.
Tunnel Mode
80
is a set of standards for wireless local area networks (WLAN), based on the IEEE 802.11 specifications
"Wi-Fi" (Wireless Fidelity)
81
A combination of a port and a network address
socket
82
an organization that oversees IP address, top level domain and Internet protocol code point allocations.
IANA
83
two different kinds of ports
1. hardware port
2. network port (connection and numerical designation)
84
Originally, every computer on the Internet was assigned a fixed identifier, called an
IP Address
85
* For computers within a private company or organization's network
* Only have to be unique within that network.
* Often start with 10. ...
Private IP Address
86
* For computers connected to the Internet
* No two can be the same
Public IP Address
87
* The network number is contained in the first octet.
* This class provides for a 24-bit host part, allowing roughly 1.6 million hosts per network
Class A (1.0.0.0 through 127.0.0.0)
88
* The network number is in the first two octets.
* This class allows for 16,320 nets with 65,024 hosts each.
Class B (128.0.0.0 through 191.255.0.0)
89
* The network number contained in the first three octets.
* This class allows for nearly 2 million networks with up to 254 hosts.
Class C (192.0.0.0 through 223.255.255.0)
90
* Experimental or reserved for special purpose use and don't specify any network.
* IP Multicast, which is a service that allows material to be transmitted to many points on an internet at one time, has been assigned addresses from within this range.
Classes D, E, and F (224.0.0.0 through 254.0.0.0)
91
There are four regional Internet registries that assign Internet addresses from the A, B & C classes
1. ARIN
2. RIPE NCC
3. APNIC
4. LACNIC
92
If all host part bits are 0, the address
network address
93
If all host part bits are 1, the address
broadcast address
93
0.0.0.0 is called
dafault route
94
127.0.0.1
looback address
95
variable length subnet masks (VLSM) to allocate IP addresses to subnets according to individual need, rather than some general network-wide rule.
CIDR
96
network allows you to break down a large network into smaller ones
subnetting
97
bitmask used to tell how much of an IP address identifies the subnetwork the host is on and how much identifies the host.
subnetmask
98
In subnetting, IPv4 addresses are broken down into three parts:
1. network
2. host
3. subnet
99
* Part of the original IEEE 802.11 standard (1999)
* A scheme used to secure wireless networks
* Uses RC4 cipher for confidentiality and the CRC-32 checksum for integrity.
* For RC4, WEP uses two key sizes: 40 bit and 104-bit; to each is added a 24-bit initialization vector (IV) which is transmitted in the clear.
Wired Equivalent Privacy
100
* Designed for use with an 802.1X authentication server, which distributes different keys to each user
* Can also be used in a less secure pre-shared key (PSK) mode.
WPA
101
* Uses the Advanced Encryption Standard (AES) block cipher
* The IEEE 802.11i architecture also contains the following components:
* 802.1X for authentication, involving the use of:
* EAP (Extensible Authentication Protocol), and
* An authentication server
* RSN (Robust Security Network) for keeping track of associations
* CCMP (Counter-Mode/CBC-Mac Protocol) to provide confidentiality, integrity and origin authentication.
* An important feature of IEEE 802i is the Four-Way Handshake
IEEE 802.11i, formally known as WPA2, in June 2004
102
* Developed by a group of electronics manufacturers
* Sony Ericsson, IBM, Intel, Toshiba, & Nokia; joined later by others
* Aptly named after a Danish king*, known for his unification of previously warring tribes from Denmark, Norway and Sweden.
* Allows any sort of electronic equipment to interconnect without wires, cables or any direct action by a user
* Short range radio solution (2.45 GHz; spread-spectrum frequency hopping technology)
* Inexpensive
Bluetooth
103
* Provides a way to connect and exchange information between devices:
* personal digital assistants (PDAs)
* mobile phones
* laptops & PCs
* printers
* digital cameras
Bluetooth
