IP Addressing and Subnetting

IP addressing and subnetting are very common Computer Networks interview topics because they show whether you understand how devices are identified and organized inside networks.

What is an IP address?

An IP address is a logical address assigned to a device in a network.

It helps:

• identify device
• identify network
• route packets correctly

IPv4

IPv4 uses 32 bits and is usually written in dotted decimal format like:

192.168.1.10

IP address parts

An IP address has:

• network part
• host part

IP Classes

Class A

• first octet range: 1 to 126
• used for very large networks

Class B

• first octet range: 128 to 191
• used for medium networks

Class C

• first octet range: 192 to 223
• used for smaller networks

Private IP ranges

Private IP ranges:

• 10.0.0.0 to 10.255.255.255
• 172.16.0.0 to 172.31.255.255
• 192.168.0.0 to 192.168.255.255

What is subnet mask?

A subnet mask separates the network part and host part of an IP address.

Example:

255.255.255.0

What is subnetting?

Subnetting is the process of dividing a large network into smaller subnetworks.

Benefits:

• better address management
• better security
• reduced broadcast traffic

Interview-style answer

IP addressing gives each device a logical address in the network, while subnetting divides a larger network into smaller sub-networks for efficient address use and management.

Quick Revision Points

• IP address is logical address
• IPv4 uses 32 bits
• subnet mask separates network and host parts
• subnetting divides large network into smaller ones
• private IP addresses are used inside local networks

Viva Questions

1. What is an IP address?
2. What is IPv4?
3. What is subnet mask?
4. What is subnetting?
5. Name private IP ranges.