Configuring Address Pool-Specific Option 1

Apart from the options in the previous sections, options can be specified using the option codes specified in RFC 2132. These options will be offered to the clients as a configuration parameter.

To configure the option 1 (Subnet mask option):

Create a pool and enter the DHCP Pool Configuration mode.
iS5comm(config)# ip dhcp pool <pool number (1-2147483647)>

iS5comm(config)# ip dhcp pool 1

A pool number is entered. The range is from 1 to 2147483647.
Configure the option 1 (Subnet mask option).
iS5comm(dhcp-config)# option 1 ip <ip address>

iS5comm(dhcp-config)# option 1 ip 255.255.0.0.

The option 1 (Subnet mask option). is configured as 255.255.0.0.
Verify the option 1 (Subnet mask option).
iS5comm(dhcp-config)# end

iS5comm# show ip dhcp server pools
```
Global Options
```
```
--------------
```
```
Code : 3, Value : 12.0.0.2
```
```
Pool Id : 1
```
```
-------------------------------------------
```
```
Subnet : 12.0.0.0
```
```
Subnet Mask : 255.0.0.0
```
```
Lease time : 95400 secs
```
```
Utilization threshold : 50%
```
```
Start Ip : 12.0.0.1
```
```
End Ip : 12.0.0.100
```
```
Subnet Options
```
```
--------------
```
```
Code : 1, Value : 255.255.0.0
```
Note: This option will be offered to the DHCP clients only when there is no host specific option for the client. If this option is not configured and there is no host option too, then the global option will be preferred.