This article is from the Windows NT Internet FAQ, by firstname.lastname@example.org (Steve Scoggins) with numerous contributions by others.
Yes NTAS V3.5 allows you to setup up a range of address that
the remote ras clients can request. This is called dynamic addressing
or bootp. and it works. The NTAS server is configured as a DHCP server.
When the remote pc calls in via RAS and is authenticated the NTAS server
assigns the remote pc an IP from the pool of unused IP addresses.