Data Encapsulation and Communications

Question 1

What is Encapsulation?

Answer 1

the process of breaking a message into packets; adding control and other information; and then transmitting the message through the transmission medium.

Question 2

What is the first step in data encapsulation?

Answer 2

The application layer prepares the data to be sent through the network

Question 3

What is the second step in the encapsulation process?

Answer 3

The Transport layer breaks the data into pieces called segment, adding sequencing and control information

Question 4

What is the third step in the encapsulation process?

Answer 4

The internet layer converts the segments into packets, adding logical network and device addresses

Question 5

What’s the fourth step in the encapsulation process?

Answer 5

The Link Layer converts the packets into frames, adding physical device information and a frame check sequence (FCS) footer for error detection. it also converts the frames into bits for transmission across the transmission media

Question 6

What is the purpose of the Address Resolution Protocol (ARP)?

Answer 6

To dynamically find the address of a computer you would want to talk to

Question 7

What is the first step in IP-based communications?

Answer 7

The data to be transferred is encapsulated on the sending host by moving from the top layer of the TCP/IP or OSI model to the bottom

Question 8

What is the second step in IP-based communications?

Answer 8

The data is transmitted on the network medium

Question 9

What is the third step in IP-based communications?

Answer 9

If necessary, the data is transferred to various routers, which forward the data to the appropriate network.

Question 10

What is the fourth step in IP-based communications?

Answer 10

The data is delivered to the destination host

Question 11

What is the fifth step in the IP-based communications?

Answer 11

The data received is de-encapsulated on the destination host by moving from the bottom layer of the TCP/IP or OSI model to the top.

Question 12

What is a star topology network?

Answer 12

uses a hub or switch to connect all network connections to a single physical location

Question 13

What is mesh network topology?

Answer 13

when there are multiple paths between any two nodes on a network

Question 14

What is a hybrid network topology?

Answer 14

when two or more types of network topologies are connected with each other

Question 15

Describe Carrier Sense Multiple Access/Collision Detection (CSMA/CD)

Answer 15

means that every node on the network must monitor the bus for a period of no activity before trying to send a message on that bus (carrier sense)

Question 16

What is the maximum cable length for UTP Ethernet T implementation

Answer 16

100 meters

Question 17

How many hosts can be supported on a single subnet?

Answer 17

support a maximum of 1024 hosts on a single subnet

Question 18

What is a frame

Answer 18

a unit of data that is ready to be sent on the network medium

Question 19

What is a preamble?

Answer 19

a set of alternating ones and zeros terminated by two ones (11), which mark it as a frame.

Question 20

What is a destination address

Answer 20

identifies the receiving host’s MAC address.

Question 21

What is the source address

Answer 21

identifies the sending host’s MAC address.

Question 22

What is the type in a ethernet frame

Answer 22

is two bytes and specifies the network/internet layer protocol being used.

Question 23

What is a packet

Answer 23

contains the information that needs to be transmitted from one host to the other.

Question 24

What is the pad in an ethernet frame

Answer 24

Ethernet frames are sized between 64 and 1518 bytes. If the frame is smaller than 64 bytes, the sending NIC places junk data in the pad to make it the required 64 bytes.

Question 25

What is the frame check sequence (FCS)

Answer 25

helps verify that the frame contents have arrived uncorrupted

Question 26

What is a hub

Answer 26

provides a central connecting point for multiple media segments on the same subnet. When a hub receives a signal, the hub sends out the signal to all the ports on the hub. Hubs operate in half-duplex mode because the path between devices is shared.

Question 27

What is a bridge

Answer 27

connects two segments within the same subnet. Bridges learn which side a host resides on by copying the MAC address of the source device and placing it into the MAC address table. The port number at which the frame entered is also recorded in the table and associated with the source MAC address.

Question 28

What is a switch

Answer 28

a multiport bridge. It provides the same functionality, but with a higher port density. In addition, switches provide features that cannot be found in bridges

Question 29

What does a layer 2 switch do

Answer 29

operates at the Data Link layer of the OSI model to process frames within a single physical network segment.

Question 30

What does a layer 3 switch do

Answer 30

provides all the functionality of a layer 2 switch but also provides routing functionality at the Network layer of the OSI model

Question 31

What layer of the OSI model is a router on?

Answer 31

Layer 3 device

Question 32

How does a router work?

Answer 32

forward packets through an internetwork by maintaining routing information in a database called a routing table

Question 33

What is a routing table?

Answer 33

contains the address of all known networks and routing information about that network

Question 34

What does the the routing table store?

Answer 34

``` Interface Routing path Next hop Route metric (cost) Route timeout ```

Question 35

What is convergence

Answer 35

used to describe the condition when all routers have the same (or correct) routing information.

Question 36

What functionality do routers provide over bridges and switches?

Answer 36

Support multiple routing protocols for better flexibility. Provide more features than switches or bridges, such as flow control, error detection, and congestion control. Provide multiple links between devices to support load balancing. Can connect different network architectures together. For example, a router can be used to connect an older Token Ring network to an Ethernet network.

Question 37

What layer of the OSI model is a Access Point on?

Answer 37

Layer 2

Question 38

What is a WLAN controller?

Answer 38

used to connect multiple APs through wired links

Question 39

What does a WLAN controller do?

Answer 39

Manages all of the APs that are connected to it. Configuration changes are made on the controller, then pushed out to all connected APs. Usually provides DHCP services to dynamically assign IP addressing information to wireless clients. Connects the wireless network to the internal wired network. Routes wireless traffic from the wireless network to the internal wired network (and vice versa).

Question 40

What is a firewall?

Answer 40

a software-based or hardware-based network security system that allows or denies network traffic according to a set of rules.

Question 41

How do firewalls decide what traffic comes and goes through the network

Answer 41

By ACL- Access Control List

Question 42

What is a Next Generation Firewall (NGFW)

Answer 42

combines a traditional firewall with other network device filtering functionalities such as an application firewall.

Question 43

Name some the advantages a NGFW has

Answer 43

Is application-aware Tracks the state of traffic based on layers 2 through 7 Utilizes an intrusion protection system (IPS) Tracks the identity of the local traffic device and user ( LDAP, RADIUS, Active Directory) Can be used in bridged and routed modes Utilizes external intelligence sources