Distance vector routing (RIP) in Computer Networks - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the sentence to describe the main metric used by RIP.

Computer Networks

RIP uses [1] as the metric to determine the best path to a destination.

Drag options to blanks, or click blank then click option'

Abandwidth

Bhop count

Cdelay

Dpacket loss

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing hop count with bandwidth or delay.

Thinking RIP uses complex metrics like packet loss.

RIP uses hop count as its metric, which counts the number of routers a packet passes through.

2fill in blank

medium

Complete the sentence to explain how often RIP routers send updates.

Computer Networks

RIP routers send their routing updates every [1] seconds to share their routing tables.

Drag options to blanks, or click blank then click option'

A10

B60

C30

D120

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing 10 seconds, which is too frequent.

Choosing 60 or 120 seconds, which are longer intervals.

RIP routers multicast their routing tables every 30 seconds to keep routes updated.

3fill in blank

hard

Fix the error in the statement about RIP's maximum hop count.

Computer Networks

The maximum hop count allowed in RIP is [1]; any route with a higher count is considered unreachable.

Drag options to blanks, or click blank then click option'

A15

B10

C16

D20

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing 16 as the maximum hop count instead of 15.

Confusing the unreachable value with the maximum valid hop count.

RIP considers a hop count of 16 as unreachable, so the maximum valid hop count is 15.

4fill in blank

hard

Fill both blanks to complete the description of RIP's routing update method.

Computer Networks

RIP uses [1] routing and sends updates to [2] addresses.

Drag options to blanks, or click blank then click option'

Adistance vector

Blink state

Cbroadcast

Dmulticast

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing distance vector with link state.

Thinking RIP uses broadcast instead of multicast.

RIP is a distance vector routing protocol and sends updates using multicast addresses to reduce unnecessary traffic.

5fill in blank

hard

Fill all three blanks to complete the RIP route update rule.

Computer Networks

A router updates its routing table if it receives a route with a [1] hop count, the route is [2] than the current one, and the route comes from a [3] neighbor.

Drag options to blanks, or click blank then click option'

Alower

Bhigher

Cbetter

Ddirect

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing 'higher' hop count instead of 'lower'.

Confusing 'better' with 'higher'.

Not recognizing that routes must come from direct neighbors.

RIP updates routes when it receives a route with a lower hop count, meaning a better route, and the route is from a direct neighbor.

Practice

1. What is the main metric used by Distance Vector Routing Protocol (RIP) to determine the best path?

easy

A. Hop count

B. Bandwidth

C. Delay

D. Cost

Solution

1. Step 1: Understand RIP metric

   RIP uses hop count as the metric to measure the distance to a destination network.

2. Step 2: Compare with other metrics

   Other protocols may use bandwidth, delay, or cost, but RIP specifically uses hop count.

3. Final Answer:

   Hop count -> Option A

4. Quick Check:

   RIP metric = Hop count [OK]

Hint: RIP counts hops, not speed or delay [OK]

Common Mistakes:

• Confusing hop count with bandwidth
• Thinking RIP uses delay as metric
• Assuming cost is used in RIP

2. Which of the following is the correct way RIP routers share their routing information?

easy

A. Routers send their entire routing table to neighbors periodically

B. Routers send only changed routes immediately

C. Routers broadcast only the best route to each destination

D. Routers send routing updates only when a link fails

Solution

1. Step 1: Recall RIP update method

   RIP routers send their full routing tables to all neighbors at regular intervals.

2. Step 2: Contrast with other methods

   Other protocols may send only changes or triggered updates, but RIP sends full tables periodically.

3. Final Answer:

   Routers send their entire routing table to neighbors periodically -> Option A

4. Quick Check:

   RIP sends full tables periodically [OK]

Hint: RIP sends full tables regularly, not just changes [OK]

Common Mistakes:

• Thinking RIP sends only changed routes
• Assuming RIP uses triggered updates only
• Believing RIP sends partial route info

3. Consider a RIP network where Router A has routes: Network X (2 hops), Network Y (3 hops). Router B receives this info and has Network X (1 hop), Network Y (4 hops). After update, what is Router B's hop count to Network Y?

medium

A. 3 hops

B. 2 hops

C. 5 hops

D. 4 hops

Solution

1. Step 1: Understand RIP update rule

   Router B updates routes by adding 1 hop to neighbors' hop counts.

2. Step 2: Calculate new hop count for Network Y

   Router A reports 3 hops to Network Y, so Router B's new cost is 3 + 1 = 4 hops. But Router B already has 4 hops, so it keeps 4 hops.

3. Step 3: Check if better route exists

   Router B's own route is 4 hops, neighbor's route plus 1 is also 4 hops, so it keeps 4 hops.

4. Final Answer:

   4 hops -> Option D

5. Quick Check:

   Neighbor hops + 1 = 4 hops [OK]

Hint: Add 1 hop to neighbor's count, pick smallest [OK]

Common Mistakes:

• Forgetting to add 1 hop to neighbor's count
• Choosing neighbor's hop count without adding 1
• Ignoring existing route cost

4. A RIP router is not updating its routing table correctly and keeps old routes indefinitely. What is the most likely cause?

medium

A. The router has a maximum hop count set too high

B. The router is using link-state routing instead of distance vector

C. The router is not receiving periodic updates from neighbors

D. The router is sending triggered updates too frequently

Solution

1. Step 1: Identify update mechanism in RIP

   RIP relies on periodic updates from neighbors to refresh routing tables.

2. Step 2: Analyze symptom

   If the router keeps old routes indefinitely, it likely isn't receiving these updates.

3. Final Answer:

   The router is not receiving periodic updates from neighbors -> Option C

4. Quick Check:

   No updates received = stale routes [OK]

Hint: No updates received means routes never refresh [OK]

Common Mistakes:

• Confusing routing protocol type
• Thinking hop count setting causes stale routes
• Assuming triggered updates cause stale routes

5. In a network using RIP, a router receives two routes to the same destination: one with 3 hops via Router X and another with 3 hops via Router Y. Which route will RIP choose and why?

hard

A. The route learned first, because RIP prefers the earliest route

B. Either route, because RIP considers equal hop counts as equal cost

C. The route with the lowest IP address of the next hop router

D. The route with the highest bandwidth link

Solution

1. Step 1: Understand RIP route selection

   RIP selects routes based on hop count; if multiple routes have the same hop count, they are considered equal cost.

2. Step 2: Analyze tie-breaking in RIP

   RIP can load balance across equal-cost routes or pick any; it does not prefer based on IP or bandwidth.

3. Final Answer:

   Either route, because RIP considers equal hop counts as equal cost -> Option B

4. Quick Check:

   Equal hops = equal cost, any route chosen [OK]

Hint: Equal hops mean equal cost; RIP can use either route [OK]

Common Mistakes:

• Assuming RIP prefers first learned route
• Thinking RIP uses next hop IP to decide
• Believing RIP considers bandwidth in route choice