RIP- Part 4 - BASIC INTERVIEW QUESTION

Question - 1 How to configure RIPv1 ?

Router#config t

Router(config)#router rip

Router(config-router)#network 10.0.0.0

Question - 2 How to configure RIPv2 ?

Router(config)#router rip

Router(config-router)#network 10.0.0.0

Router(config-router)#version 2

Question - 3 Can we use RIP in inter-network having more than 15 routers ?

Yes, If connected with Broadcast Multi Access Network. In BMA (Broadcast Multi Access ) more than two router connected via switch within a same network.

Question - 4 What is difference between RIP and RIPng ?

RIP is for IPv4 and RIPng for IPv6.

Question - 5 What is multicast address of RIPv2 ?

Multicast Address of RIPv2 is 224.0.0.9

Question - 6 How do you stop RIP updates from propagating out an interface on a router ?

Holding Down RIP Propagations

There are a few different ways to stop unwanted RIP updates from propagating across your LANs and WANs, and the easiest one is through the passive-interface command. This command prevents RIP update broadcasts from being sent out a specified interface, yet that same interface can still receive RIP updates.

Here’s an example of how to configure a passive-interface on a router using the CLI:

Router#config t

Router(config)#router rip

Router(config-router)#network 192.168.20.0

Router(config-router)#passive-interface serial 0/0

This command will stop RIP updates from being propagated out serial interface 0/0, but serial interface 0/0 can still receive RIP updates.

Question - 7 If a RIPv2 router advertise it’s route, would it be received by all the devices on the network ?

Rip v2 is multicast. So the route advertisement would be received only by devices which has Rip v2 enabled. If the advertisement was Rip v1, then it would be received by all devices on the network as Rip v1 is broadcast.

Question - 8 How can a Rip route advertisement be blocked on a specific interface ?

By using the passive interface command.

Question - 9 If a static route and a RIP learned route are available on a router which entry would be chosen by the router to forward the packet ?

Static route would be chosen since it has lower administrative distance than Rip

Question - 10 Can a subnet mask information be stored in a RIPv1 packet ?

Rip v1 is a classfull routing protocol. It does not understand classless concepts like Subnets. So it is not possible

Question - 11 Is a subnet mask field available in a RIPv2 packet ?

Ripv2 is classless routing protocol. A ripv2 packet has a field to include the subnet mask information.

Question - 12 How can we manipulate metrics in RIP ?

We can manipulate metrics in RIP through the Offset-Lists.   

Question - 13 What is Offset-List ?

• An offset list is the process of Traffic Engineering.  
• This technique used for increasing incoming and outgoing metrics to routes learned via EIGRP or RIP. 
• The offset value is added to the routing metric.
• An offset list that specifies an interface type and interface number is considered to be an extended list and takes precedence over an offset list that is not extended. 
• Therefore, if an entry passes the extended offset list and a normal offset list, the offset of the extended offset list is added to the metric.
• An Offset List Can Be Used to Prefer a Faster Path.

Question - 14 Can we use Offset-list in Link State Routing Protocols ?

No, Offset lists are only used with distance vector routing protocols.

Question - 15 How to configure Offset-List ?

To configure an offset to incoming and outgoing metrics to routes learned via EIGRP or RIP, use the offset-list {access-list-number | access-list-name} {in | out} offset [interface-type interface-number]

access-list-number | access-list-name ---Standard access list number or name to be applied. Access list number 0 indicates all access lists. If the offset value is 0, no action is taken.

in---Applies the access list to incoming metrics.

out---Applies the access list to outgoing metrics.

offset---Positive offset to be applied to metrics for networks matching the access list. If the offset is 0, no action is taken.

interface-type interface-number---(Optional) Interface type and number to which the offset list is applied.

Question - 16 How to configure Offset-List in RIP ?

Check Chapter RIP-OFFSET LISTS CONFIGURATION

Question - 17 What is incoming metrics ?

• The incoming metric modifies the cost of an individual segment when a route across the segment is imported into the routing table.
•  For example, if you set the incoming metric on the segment to 3, the individual segment cost along the link is changed from 1 to 3.
• The increased cost affects all route calculations through that link. Other routes that were previously excluded because of a high hop count might now be selected into the router's forwarding table.

Question - 18 What is outgoing metrics ?

• The outgoing metric modifies the path cost for all the routes advertised out a particular interface. 
• Unlike the incoming metric, the outgoing metric modifies the routes that other routers are learning and thereby controls the way they send traffic.

Question - 19 What are limitations of RIP ?

• The hop count limit in RIP is 15, Without using RMTI, Hop count cannot exceed 15, in the case that it exceeds this limitation, it will be considered invalid or routes will be dropped.
• Most of RIP networks are flat. RIP has  no any concept of areas or boundaries in RIP networks (but aggregation is possible).
• RIPv1 does not support VLSM (Variable Length Subnet Masking)
• RIP has slow convergence due to periodic routing update and count to infinity problems. 

Question - 20 Explain loop avoidance mechanism in RIP.

Maximum Hop Count 

• RIP permits a hop count of up to 15, so anything that requires 16 hops is deemed unreachable.
• In other words, after a loop of 15 hops, Network will be considered down. 
• Thus, the maximum hop count will control how long it takes for a routing table entry to become invalid or questionable.

Split Horizon

• This reduces incorrect routing information and routing overhead in a distance vector network by enforcing the rule that routing information cannot be sent back in the direction from which it was received.

Route Poisoning

• When Network goes down, Router initiates route poisoning by advertising Network with a hop count of 16, or unreachable (sometimes referred to as infinite).

Hold-downs

• A hold-down prevents regular update messages from reinstating a route that is going up and down (called flapping). Typically, this happens on a serial link that’s losing connectivity and then coming back up..

Question - 21 Explain disadvantages of RIP ?

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Anubhav Upadhyay

Hello and welcome to networktopic Blog. My name is Anubhav. I am a Senior Network Egineer. I have created this blog specially to serve interview questions and answer on Network Routing and Switching, I will try my best to serve correct and updated networking knowledge for you as per my corporate experience.

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