# Q1B · Host bits and address counts

Subject: Computer Networks

Exam: M2

Reader: https://deep-learning-study-room.vercel.app/cn/#m2/mocks/mock-a/q1b

Canonical: https://deep-learning-study-room.vercel.app/read/cn/m2/mocks/mock-a--q1b/

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

### Question. For IPv4 /27, find the number of host bits, total addresses and ordinary usable host addresses. [2 practice marks]

#### Answer

## Given

p=27; ordinary IPv4 broadcast subnet.

## To find

h, total and usable counts.

## Formula and why



$$
h=32-p,\quad N=2^h,\quad U=N-2
$$



Two boundary addresses are reserved under these ordinary rules.

## Step-by-step solution

1. Host bits: 32−27=5.
2. Total addresses: 2⁵=32.
3. Usable hosts: 32−2=30.

**Final answer:** 5 host bits, 32 total, 30 usable.

#### Practical example

A request for 32 usable devices would need a larger subnet.