Use these instructions to determine the zone name for a Reverse DNS Zone.
Classless Address Block Example
| Instructions | Example |
|---|---|
| 1. Take your network IP address. | 192.168.15.224/27 |
| 2. Remove the netmask portion of the address, that’s the number after the slash (/) in the prior example. | 192.168.15.224 |
| 3. Reverse the order of the remaining octets. | 224.15.168.192 |
| 4. Add ‘in-addr.arpa’ to the end. | 224.15.168.192.in-addr.arpa |
| 5. Add the netmask back into the address. | 224-27.15.168.192.in-addr.arpa* |
In this example, 224-27.15.168.192.in-addr.arpa is your Reverse DNS Zone Name.
* NOTE: Some Assigning Authorities require you to use a slash (/) instead of a dash (-) in the reverse address.
Ask which character to use when you contact your assigning authority to delegate the reverse address.
Full Address Block Example
| Instructions | Example |
|---|---|
| 1. Take your network IP address. | 192.168.15.0 |
| 2. Remove the netmask portion of the address, that’s the last number in the set of 4. | 192.168.15 |
| 3. Reverse the order of the remaining three octets. | 15.168.192 |
| 4. Add ‘in-addr.arpa’ to the end. | 15.168.192.in-addr.arpa |
In this example, 15.168.192.in-addr.arpa is your Reverse DNS Zone Name.