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CCNA Exploration Chapter 4 Distance Vector. Study questions.

4.1
Name three distance vector routing protocols.

RIP, IGRP, EIGRP.

What is the largest number of hops that can appear as the metric for a RIP route?

15

What metrics can be used by IGRP?

Bandwidth, delay, load, reliability.

How often do the different distance vector routing protocols send out their routing tablein periodic updates?

RIP – every 30 seconds
IGRP – every 90 seconds
EIGRP – does not send out routing table as periodic updates.

What algoritm does EIGRP use to calculate best paths?

DUAL (Diffusing Update Algorithm)

What two pieces of information does a distance vector routing protocol have about a path?

The port leading to the network (vector) and the “distance” to the network asmeasured by the metric.

What is inefficient about the typical distance vector method of sending updates?

Typically, complete routing tables are sent at regular intervals even if the network has not changed. This uses bandwidth, and takes up router processing time.

What does a routing algorithm do?

Sends and receives routing information.
Calculates best paths and puts them in therouting table.
Detects and reacts to topology changes.

What are the advantages of using a distance vector routing protocol rather than link state?

Easier to configure and maintain.
Requires less router processing power and memory.

What are the disadvantages of using a distance vector routing protocol rather than link state?

Generally slow to converge
Do not scale well to largernetworks
Routing loops may occur.

Why is it better to use a classless routing protocol than a classful routing protocols?

Classless protocols support VLSM.

In which ways is EIGRP not a typical distance vector routing protocol, but more like a link state routing protocol?

Fast to converge, suitable for large networks, complex to configure, needs large amounts of processing power and RAM.Does a router save its routing table in NVRAM as part of its configuration?

No. The routing table is not saved.

When a router starts up and loads its configuration, which routes can it put in its routing table at first?

Directly connected routes. The information comes from the interface configuration.







The five routers have just been switched on. They have a savedconfiguration including IP addresses on the interfaces and RIP routing. How many routing updates need to be sent before the network is converged?

Four.

Which two factors determine the speed of convergence of a network?

The time routers take to pass routing information from one end of the network to the other. The time a router takes to process the information it receives and calculate best paths.How often does RIP send updates by default?

Every 30 seconds.

To which address does RIP version 1 send updates?

It broadcasts them to 255.255.255.255.

What is the default value of the invalid timer in RIP, and what is it used for?

180 seconds. If a route is not refreshed – it does not appear in routing updates – for 180 seconds then it is marked as invalid. Its metric is changedto 16 hops.

What is the default value of the flush timer in RIP, and what is it used for?

240 seconds. If a route is not refreshed – it does not appear in routing updates – for 240 seconds then it is removed from the routing table.

EIGRP sends non-periodic, partial, bounded updates. What does this mean?

It does not send updates at regular intervals. It does not send its whole routingtable, but only sends information about changes in topology/availablilty of routes. It does not send the updates to all routers, but only to the routers that need the information.

What is a triggered update?

A triggered update is to speed up convergence. When a router detects a change – interface up/down, route added/removed – it sends an update to neighbours at once. Those neighbours then...