The remote access server (RAS) or network access server (NAS) is a combination of a modem bank and a high-end router. The network access serve acts as a router and concentrator for internet protocol (IP) packets that arrive via the data connections. The remote access servers enable the operator of a telecommunications network to connect its subscribers directly to the web without the need for an external ISP. The data connections to a remote access server are established over plain old
telephone service (POTS) phone lines or integrated services digital network (ISDN) lines. Many remote access server systems use a dynamic host configuration protocol (DHCP) as a standard messaging protocol to dynamically allocate network addresses such as internet protocol (IP) addresses. IP address is typically randomly assigned from a pool of IP addresses reserved for the subscriber to which the newly connected computer is attached.
