# Q4 · RIP metric and next hop

Subject: Computer Networks

Exam: M2

Reader: https://deep-learning-study-room.vercel.app/cn/#m2/mocks/mock-c/q4

Canonical: https://deep-learning-study-room.vercel.app/read/cn/m2/mocks/mock-c--q4/

Q1(a)+Q1(b) compulsory; choose any two of Q2/Q3/Q4 · 10 marks attempted

### Question. For a destination Z, RIP neighbour B advertises metric 15 and neighbour C advertises metric 4. Each local link adds one hop. Compute both candidate metrics and the selected route. [3 practice marks]

#### Answer

## Given

B advertises 15; C advertises 4; each local cost=1. RIP infinity=16.

## To find

Candidate metrics and usable next hop.

## Formula and why



$$
\text{candidate}=\min(16,1+\text{advertised metric})
$$



RIP caps its metric at 16, representing unreachable.

## Step-by-step solution

1. Via B: min(16,1+15)=16 → unreachable.
2. Via C: min(16,1+4)=5 → reachable.
3. Select C, the finite lower-metric route.

**Final answer:** route via C at metric 5; B’s route is unreachable.

#### Practical example

Metric 16 is not a valid 16-hop route.