Chapter 4: IPv4 Routing & Addressing

Question 1

The process of hosts and routers forwarding IP packets (Layer 3 PDUs), while relying on the underlying LANs and WANs to forward the bits.

Answer 1

IP Routing

Question 2

Addresses used to identify a packet’s source and destination host computer. Addressing rules also organize addresses into groups, which greatly assists the routing process.

Answer 2

IP addressing

Question 3

A protocol that aids routers by dynamically learning about the IP address groups so that a router knows where to route IP packets so that they go to the right destination host.

Answer 3

IP routing protocol

Question 4

Name two functions of OSI Layer 3 protocols?

Answer 4

Logical Addressing & Path Selection

Question 5

What does a router normally use when making a decision about routing TCP/ IP packets?

Answer 5

Destination IP address

Question 6

What are two functions of a routing protocol?

Answer 6

Learning and advertising routes to neighbouring routers.

Question 7

How many bits is an IP address and in what format?

Answer 7

32 bits in for 8 bit decimal separated groups.

Question 8

A packet with a destination IP address not within the senders subnet is directed where?

Answer 8

The default gateway.

Question 9

Upon receipt of a frame a router examines the data-link Frame Check Sequence for what purpose?

Answer 9

Error Detection.

Question 10

How does a router primarily find the best route for an IP packet?

Answer 10

By consulting its routing table.

Question 11

To make a decision about IP packet routing what two pieces of information could a router find in its routing table?

Answer 11

The outgoing interface and possibly the next-hop router IP address.

Question 12

After a route is chosen what is the final step a router carries out before forwarding an IP packet?

Answer 12

The router encapsulates the IP packet inside a new data-link header and trailer.

Question 13

What are the four steps a router carries out during IP Packet forwarding?

Answer 13

Error detection, removal of data-link header and trailer, route identification, re-encapsulation.

Question 14

A generic reference to any routing protocol’s messages in which it sends routing information to a neighbor.

Answer 14

A routing update.

Question 15

An application layer protocol used throughout the Internet for translating host names into their associated IP addresses.

Answer 15

DNS Domain Name System

Question 16

An Internet protocol used to map an IP address to a MAC address. Defined in RFC 826.

Answer 16

ARP Address Resolution Protocol.

Question 17

An Internet Control Message Protocol (ICMP) echo message and its reply; this is often used in IP networks to test the reachability of a network device.

Answer 17

Ping.

Question 18

The format used for IP version 4 addresses, in which four decimal values are used, separated by periods.

Answer 18

DDF Dotted Decimal Format

Question 19

The version of the Internet Protocol defined in an old RFC 791, standardized in 1980, and used as the basis of TCP/ IP networks and the Internet for over 30 years.

Answer 19

IPv4

Question 20

An IP address that represents a single interface. In IPv4, these addresses come from the Class A, B, and C ranges.

Answer 20

Unicast IP address.

Question 21

The process of subdividing a Class A, B, or C network into smaller groups.

Answer 21

Subnetting.

Question 22

A list of routes in a router, with each route listing the destination subnet and mask, the router interface out which to forward packets destined to that subnet, and as needed, the next-hop router’s IP address.

Answer 22

Routing Table.

Question 23

A set of messages and processes with which routers can exchange information about routes to reach subnets in a particular network.

Answer 23

Routing protocol.