It sounds like the RAS-DHCP addresses are not expiring. I googled and checked
MS. From what I found it appears based on how the DHCP server is configured
the it may be doling out 10 IPs for each RAS client.
The following is from MS 2003 server website.
Using Routing and Remote Access servers with DHCPThe DHCP Server service can
be deployed along with the Routing and Remote Access service to provide
remote access clients with a dynamically assigned IP address during
connection. When these services are used together on the same server
computer, the information provided during dynamic configuration is provided
differently than in the case of typical DHCP configuration for LAN-based
clients.
In LAN environments, DHCP clients negotiate and receive the following
configuration information, based entirely on settings configured in the DHCP
console for the DHCP server:
A leased IP address provided from the available address pool of an active
scope on the DHCP server. The DHCP server directly manages and distributes
the address to the LAN-based DHCP client.
Additional parameters and other configuration information provided through
assigned DHCP options in the address lease. The values and list of options
used correspond to option types configured and assigned on the DHCP server.
When a Routing and Remote Access server provides dynamic configuration for
dial-up clients, it first performs the following steps:
When the Routing and Remote Access server starts with the Use DHCP to assign
remote TCP/IP addresses option, it instructs the DHCP client to obtain 10 IP
addresses from a DHCP server.
The remote access server utilizes the first of these 10 IP addresses
obtained from the DHCP server for the remote access server interface.
The remaining nine addresses are allocated to TCP/IP-based clients as they
dial in to establish a session with the remote access server.
IP addresses that are freed when remote access clients disconnect are
reused. When all 10 IP addresses are used, the remote access server obtains
10 more from a DHCP server. When the Routing and Remote Access service is
stopped, all IP addresses obtained through DHCP are released.
When the Routing and Remote Access server uses this type of proactive
caching of DHCP address leases for dial-up clients, it records the following
information for each lease response it obtains from the DHCP server:
The IP address of the DHCP server
The client leased IP address (for later distribution to the Routing and
Remote Access client)
The time at which the lease was obtained
The time at which the lease expires
The duration of the lease
All other DHCP option information returned by the DHCP server (such as
server, scope, or reservation options) is discarded. When the client dials in
to the server and requests an IP address (that is, when Server Assigned IP
Address is selected), it uses a cached DHCP lease to provide the dial-up
client with dynamic IP address configuration.
When the IP address is provided to the dial-up client, the client is unaware
that the IP address has been obtained through this intermediate process
between the DHCP server and the Routing and Remote Access server. The Routing
and Remote Access server maintains the lease on behalf of the client.
Therefore, the only information that the client receives from the DHCP server
is the IP address lease.
In dial-up environments, DHCP clients negotiate and receive dynamic
configuration using the following modified behavior:
A leased IP address from the Routing and Remote Access server cache of DHCP
scope addresses. The Routing and Remote Access server obtains and renews its
cached address pool with the DHCP server.
If additional parameters and other configuration information provided
through assigned DHCP options in the address lease is normally provided by
the DHCP server, this information is returned to the Routing and Remote
Access client based on TCP/IP properties configured on the Routing and Remote
Access server.
