| Option Code | Option name | Description | Data Type | Supported | Is Predefined? | Grammar | Example |
| 1 | no-client-update | When the client sends this, if it is true, it means the client will not attempt to update its A record. When sent by the server to the client, it means that the client should not update its own A record. | flag | 1 | 1 | flag | values : true or false or on or off Example : true |
| 2 | server-update | When the client sends this to the server, it is requesting that the server update its A record. When sent by the server, it means that the server has updated (or is about to update) the client’s A record. | flag | 1 | 1 | flag | values : true or false or on or off Example : true |
| 3 | encoded | If true, this indicates that the domain name included in the option is encoded in DNS wire format, rather than as plain ASCII text. The client normally sets this to false if it doesn’t support DNS wire format in the FQDN option. The server should always send back the same value that the client sent. When this value is set on the configuration side, it controls the format in which the fqdn.fqdn suboption is encoded. | flag | 1 | 1 | flag | values : true or false or on or off Example : true |
| 4, 5 | rcode1, rcode2 | These options specify the result of the updates of the A and PTR records, respectively, and are only sent by the DHCP server to the DHCP client. The values of these fields are those defined in the DNS protocol specification. | flag | 1 | 1 | flag | values : true or false or on or off Example : true |
| 6 | fqdn | Specifies the domain name that the client wishes to use. This can be a fully-qualified domain name, or a single label. If there is no trailing ´.´ character in the name, it is not fully-qualified, and the server will generally update that name in some locally-defined domain. | quoted_string | 1 | 1 | text | Type : fqdn |
| 7 | hostname | This option should never be set, but it can be read back using the option and config-option operators in an expression, in which case it returns the first label in the fqdn.fqdn suboption - for example, if the value of fqdn.fqdn is "foo.example.com.", then fqdn.hostname will be "foo". | flag | 1 | 1 | --never set-- | values : true or false or on or off Example : true |
| 8 | domainname | This option should never be set, but it can be read back using the option and config-option operators in an expression, in which case it returns all labels after the first label in the fqdn.fqdn suboption - for example, if the value of fqdn.fqdn is "foo.example.com.", then fqdn.domainname will be "example.com.". If this suboption value is not set, it means that an unqualified name was sent in the fqdn option, or that no fqdn option was sent at all. | flag | 1 | 1 | --never set-- | values : true or false or on or off Example : true |