In the backtrack repo the dhcp packages are a bit outdated, below i a list of the packages that should be updated

dhcp-client: DHCP client transitional package
dhcp3-client: DHCP client
dhcp3-client-udeb: DHCP Client for debian-installer
dhcp3-common: common files used by all the dhcp3* packages
dhcp3-dev: API for accessing and modifying the DHCP server and client state
dhcp3-relay: DHCP relay daemon
dhcp3-server: DHCP server for automatic IP address assignment
dhcp3-server-ldap: DHCP server able to use LDAP as backend

the biggest reason is for bug fixes, especially dhcp3-server

source: https://launchpad.net/ubuntu/+source/dhcp3