b09f51b5_HCP_Overview__Support____Cisco__DHCP_Option_Name
[DHCP Option Code] 12 [Description] Specifies the name of the client. The name may or may not be qualified with the local domain name. [DHCP Option Name] 
Hostname option
IP Addressing: DHCP Configuration Guide, Cisco IOS XE Release 3S (Cisco ASR 1000) - DHCP Overview [Support] - Cisco