Question : Client pc's cannot resolve external domain

This is SBS2003 with 8 XP clients. After 4 years of working quite well, last week the client pc's stopped being able to resolve the external domain from within the internal network. This gave the following problems:

1. Clients could not look at the company website by entering the external domain name
2. Clients with pop mail accounts could not retrieve their mail.
3. The boss could not log into the server with TS unless he used the internal address.

For now, i've created a forward lookup zone in the DNS server. This has fixed the problem, but I'm curious to know what has changed to cause this problem.

Answer : Client pc's cannot resolve external domain

>>"Two of the clients are using laptops and work off site. So I cant have their DNS pointed at the SBS Server. "
When in the office you have no choice they have to point to the SBS and only the SBS. However if they are using DHCP and the DHCP scope is configured correctly this is not a problem as it looks after itself. On occasion you have to reboot the laptop when you bring it in the office to make sure they get the DHCP changes.

Often times you cannot connect to the external domain (public IP) from within the office as many routers do not support "loopback" connections. Since you changed the router this may be the case.