The number one thing to do when troubleshooting any service is to determine if it’s even breathing or not. First check the Services to see if it’s running. The Services applet is traditionally found with Administrative tools, but is also available with Computer Management and also within Control Panel.

If you’re worried about DHCP functionality, go to a client machine and run IPCONFIG /RELEASE, and then IPCONFIG /RENEW. Of course, this assumes that the server has general network access, itself. With DHCP, you also need to make sure that the DHCP scope has been activated, which must be done after it’s created. You might also encounter client messages indicating a duplicate IP address. If this happens, the problem is that another DHCP server on the network is assigning the same addresses to computers.

DNS is a bit harder to troubleshoot. Again, make sure that the service is up and running. You can also check that DNS is resolving. Sometimes it take a few minutes for DNS resolution to work on client machines, but beware - check the event logs to see if there are any DNS-related messages which would indicate further problems (such as a network card driver incompatibility).

Finally, you can run NSLOOKUP with an IP address for a system that you know is outside of your local LAN, or an address that would normally be handled by DNS. NSLOOKUP does the reverse of standard DNS, and should tell you the FQDN that DNS is returning for that particular IP address. If it fails to do so, you need to check DNS connectivity by PINGing the DNS server from a client. You also need to check and make sure that the results of NSLOOKUP are actually valid and true: if they’re not, there’s a problem with the DNS database and requires some reconfiguration.