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	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	.193 - .222	.223
.224	.225 - .254	.255
Subnet Mask Subnet Bits/Aggregate Number of Subnets Network Address	255.255.255.240 16 Host IP Range	Hex Mask Host Bits Hosts per Subnet Broadcast Addresses	0xfffffff0 4 14
.0	.1 “ .14	.15
.16	.17 - .30	.31
.32	.33 - .46	.47
.48	.49 - .62	.63
.64	.65 - .94	.79
.80	.81 - .94	.95
.96	.97 - .110	.111
.112	.113 - .126	.127
.128	.129 - .142	.143
.144	.145 - .158	.159
.160	.161 - .174	.175
.176	.177 - .190	.191
.192	.193 - .206	.207
.208	.209 - .222	.223
.224	.225 - .238	.239
.240	.241 - .254	.255
Subnet Mask Subnet Bits/Aggregate Number of Subnets Network Address	255.255.255.248 32 Host IP Range	Hex Mask Host Bits Hosts per Subnet Broadcast Addresses	0xfffffff8 3 6
.0	.1 “ .6	.7
.8	.9 - .14	.15
.16	.17 - .22	.23
.24	.25 - .30	.31
.32	.33 - .38	.39
.40	.41 - .46	.47
.48	.49 - .54	.55
.56	.57 - .62	.63
.64	.65 - .70	.71
.72	.73 - .78	.79
.80	.81 - .86	.87
.88	.89 - .94	.95
.96	.97 - .102	.103
.104	.105 - .110	.111
.112	.113 - .118	.119
.120	.121 - .126	.127
.128	.129 - .134	.135
.136	.137 - .142	.143
.144	.145 - .150	.151
.152	.153 - .158	.159
.160	.161 - .166	.167
.168	.169 - .174	.175
.176	.177 - .182	.183
.184	.185 - .190	.191
.192	.193 - .198	.199
.200	.201 - .206	.207
.208	.209 - .214	.215
.216	.217 - .222	.223
.224	.225 - .230	.231
.232	.233 - .238	.239
.240	.241 - .246	.247
.248	.249 - .254	.255
Subnet Mask Subnet Bits/Aggregate Number of Subnets Network Address	255.255.255.252 30 64 Host IP Range	Hex Mask Host Bits Hosts per Subnet Broadcast Addresses	0xfffffffc 2 2
.0	.1 “ .2	.3
.4	.5 - .6	.7
.8	.9 - .10	.11
.12	.13 - .14	.15
.16	.17 - .18	.19
.20	.21 - .22	.23
.24	.25 - .26	.27
.28	.29 - .30	.31
.32	.33 - .34	.35
.36	.37 - .38	.39
.40	.41 - .42	.43
.44	.45 - .46	.47
.48	.49 - .50	.51
.52	.53 - .54	.55
.56	.57 - .58	.59
.60	.61 - .62	.63
.64	.65 - .66	.67
.68	.69 - .70	.71
.72	.73 - .74	.75
.76	.77 - .78	.79
.80	.81 - .82	.83
.84	.85 - .86	.87
.88	.89 - .90	.91
.92	.93 - .94	.95
.96	.97 - .98	.99
.100	.101 - .102	.103
.104	.105 - .106	.107
.108	.109 - .110	.111
.112	.113 - .114	.115
.118	.117 - .119	.116
.120	.121 - .122	.123
.124	.125 - .126	.127
.128	.129 - .130	.131
.132	.133 - .134	.135
.136	.137 - .138	.139
.140	.141 - .142	.143
.144	.145 - .146	.147
.148	.149 - .150	.151
.152	.153 - .154	.155
.156	.157 - .158	.159
.160	.161 - .162	.163
.164	.165 - .166	.167
.168	.169 - .170	.171
.172	.173 - .174	.175
.176	.177 - .178	.179
.180	.181 - .182	.183
.184	.185 - .186	.187
.188	.189 - .190	.191
.192	.193 - .192	.195
.196	.197 - .198	.199
.200	.201 - .202	.203
.204	.205 - .206	.207
.208	.209 - .210	.211
.212	.213 - .214	.215
.216	.217 - .218	.219
.220	.221 - .222	.223
.224	.225 - .226	.227
.228	.229 - .230	.231
.232	.233 - .234	.235
.236	.237 - .238	.239
242	.241 - .243	.240
244	.245 - .246	.247
.248	.249 - .250	.251
252	.253 - .254	.255
Subnet Mask Subnet Bits/Aggregate Number of Subnets	255.255.255.255 32 255	Hex Mask Host Bits Hosts per Subnet	0xffffffff 1