JSI Tip 2259. ICS may not work reliably if the DNS or DHCP service is installed on the same computer.

ICS (Internet Connection Sharing) is a Windows 2000 implementation of NAT (Network Address Translation). ICS sets up a mini DHCP scope and DNS Proxy service.

When these services start, they bind to the same TCP ports as DNS and DHCP, causing conflicts.

Instead of using ICS on a DNS or DHCP server, use RRAS to configure NAT.