Check Point NG/AI: Next Generation with Application Intelligence Security Administration

Appendix A: Class C Subnet Mask Cheat Sheet

This cheat sheet can come in handy when working with network addresses and subnet masks. A standard netmask is written 255.255.255.0 which is equivalent to the aggregate /24. Using aggregates has become popular because computer people tend to be lazy and it only requires three keystrokes.

Table A.1: Netmasks and Aggregates

Netmasks and Aggregates

Subnet Mask
Subnet Bits/Aggregate
Number of Subnets
Network Address
0

255.255.255.0
24
1
Host IP Range
1 - .254

Hex Mask
Host Bits
Hosts per Subnet
Broadcast Addresses
.255

0xffffff00
8
254

Subnet Mask
Subnet Bits/Aggregate
Number of Subnets
Network Address
.0
.128

255.255.255.128
25
2
Host IP Range
.1 - .126
.129 - .254

Hex Mask
Host Bits
Hosts per Subnet
Broadcast Addresses
.127
.255

0xffffff80
7
126

Subnet Mask
Subnet Bits/Aggregate
Number of Subnets
Network Address
.0
.64
.128
.192

255.255.255.192
26
4
Host IP Range
.1 - .62
.65 - .126
.129 - .190
.193 - .254

Hex Mask
Host Bits
Hosts per Subnet
Broadcast Addresses
.63
.127
.191
.255

0xffffffc0
6
62

Subnet Mask
Subnet Bits/Aggregate
Number of Subnets
Network Address
.0
.32
.64
.96

255.255.255.224
27
8
Host IP Range
.1 - .30
.33 - .62
.65 - .94
.97 - .126

Hex Mask
Host Bits
Hosts per Subnet
Broadcast Addresses
.31
.63
.95
.127

0xffffffe0
5
30

Network Address

Host IP Range

Broadcast Addresses

.128

.129 - .158

.159

.160

.161 - .190

.191

.192