DHCP is Dynamic host configuration protocol. It is defined in RFC 2131 and it follows DORA exchange of messages ( DHCPDISCOVER, DHCPOFFER, DHCPREQUEST, DHCPACK)
We have various DHCP options:
The DHCP options ( 0-255) are divided into two ranges
1) 1-127 are publicly defined options and are now allocated in accordance to RFC 2939
2) 128-253 are site specific option
Options 0 is "pad option" and option 255 is "End option"
RFC related to common DHCP options:
1) DHCP options and BOOTP vendor extensions : RFC 2132
2) DHCP DHCP Relay Agent Information Option : RFC 3046 : option 82
3) Dynamic Host Configuration Protocol (DHCP) Domain Search Option : RFC 3397
4) Vendor-Identifying Vendor Options for Dynamic Host Configuration Protocol version 4 (DHCPv4) : RFC 3925
5) The Name Service Search Option for DHCP : RFC 2937
6) The IPV4 Subnet Selection option for DHCP : RFC 3011
7) Dynamic Host Configuration Protocol (DHCP-for-IPv4) Option for Session Initiation Protocol (SIP) Servers : RFC 3361
IPv6 Related DHCP RFC
RFC 3315, Dynamic Host Configuration Protocol for IPv6 (DHCPv6)
RFC 3633, IPv6 Prefix Options for Dynamic Host Configuration Protocol (DHCP) version 6
RFC 4649, Dynamic Host Configuration Protocol for IPv6 (DHCPv6) Relay Agent Remote-ID Option
DHCP RFC for MoS and ANDSF
Dynamic Host Configuration Protocol (DHCPv4 and DHCPv6) Options for IEEE 802.21 Mobility Services (MoS) Discovery : RFC 5678
DHCPv4 and DHCPv6 Options for Access Network Discovery and Selection Function (ANDSF) Discovery : RFC 6153
Good link which has all the options
http://www.ietf.org/assignments/bootp-dhcp-parameters/bootp-dhcp-parameters.txt
