b09f51b5_HCP_Overview__Support____Cisco__DHCP_Option_Name
[DHCP Option Code] 3 [Description] Specifies a list of IP addresses for routers on the client's subnet, usually listed in order of preference. [DHCP Option Name] 
Router option
IP Addressing: DHCP Configuration Guide, Cisco IOS XE Release 3S (Cisco ASR 1000) - DHCP Overview [Support] - Cisco