Subnet Mask
A 32-bit number that divides an IP address into network and host portions.
Also: netmask · CIDR prefix
Definition
A subnet mask is a 32-bit number used to distinguish the network portion of an IP address from the host portion, enabling routers to determine whether traffic should stay on the local network or be forwarded to another network. Written in dotted-decimal notation (e.g., 255.255.255.0) or CIDR notation (e.g., /24), subnetting allows network administrators to divide large networks into smaller, more manageable segments, improving security and performance.
Example
“With a subnet mask of 255.255.255.0, all devices with IP addresses 192.168.1.1 through 192.168.1.254 are on the same local network.”
Usage Examples
- 1
“The team applied subnet mask best practices to improve their networking outcomes significantly.”
- 2
“Understanding subnet mask is essential for anyone building a career in IT & Technology.”
When & How to Use
Use 'Subnet Mask' when working in Networking contexts where a subnet mask is a 32-bit number used to distinguish the network portion of an ip address from the host portion, enabling routers to determine whether traffic should stay on the local network or be forwarded to another network.
- ▸Applying subnet mask principles during a networking project or initiative
- ▸Explaining subnet mask to a junior team member or stakeholder unfamiliar with IT & Technology
- ▸Evaluating options or proposals using subnet mask as a decision-making criterion
Etymology & Origin
The term 'Subnet Mask' derives from Latin roots and entered IT & Technology professional usage as the field formalised in the 20th century.
History & Evolution
The concept of subnet mask has evolved alongside IT & Technology. Early practitioners relied on informal methods; structured approaches emerged with the professionalisation of networking in the mid-20th century. Today, subnet mask is a standard part of IT & Technology practice globally.
Synonyms
- network mask
- CIDR notation
- netmask
- subnet prefix
Images
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Related Terms
- ip-address
- cidr
- subnetting
- router