What does a subnet mask do in IPv4 addressing? Learn how subnet masks define the network and host portions of an IP address, supporting efficient routing and network management—essential for the Cisco Certified Support Technician (CCST) Networking 100-150 exam.
Table of Contents
Question
What is the purpose of a subnet mask in IPv4 addressing?
A. Identifies the default gateway
B. Distinguishes public and private IP addresses
C. Encrypts network traffic
D. Assigns a static IP to each device
E. Defines the network and host portions of an IP address
Answer
E. Defines the network and host portions of an IP address
Explanation
The subnet mask separates an IP address into network and host portions for routing.
The purpose of a subnet mask in IPv4 addressing is to define the network and host portions of an IP address.
A subnet mask is a 32-bit number that distinguishes which part of an IPv4 address identifies the network and which part identifies the host within that network.
In binary, the subnet mask consists of a series of ones (1s) followed by zeros (0s). The ones indicate the bits used for the network prefix, while the zeros indicate the bits used for host identification.
For example, with the IP address 192.168.123.132 and subnet mask 255.255.255.0:
- The first three octets (255.255.255) represent the network portion.
- The last octet (0) represents the host portion.
This separation allows devices and routers to determine whether another device is on the same network or a different one, enabling correct routing of packets within and between networks.
Without a subnet mask, it would be impossible to distinguish the network from the host portion of an IP address, making efficient routing and network segmentation unmanageable.
A subnet mask enables network devices to interpret which part of an IP address refers to the network and which part refers to the specific device (host), ensuring proper routing and network organization.
Cisco Certified Support Technician (CCST) Networking 100-150 certification exam practice question and answer (Q&A) dump with detail explanation and reference available free, helpful to pass the Cisco Certified Support Technician (CCST) Networking 100-150 exam and earn Cisco Certified Support Technician (CCST) Networking 100-150 certification.