In your DHCP scope (the info that you are providing to the clients) you should have your DNS server IPs, gateway IPs, WINS IPs, etc. anyway. Did you not have an option in your client PCs' IP settings for DNS? If not, did the client PCs have a hardcoded DNS server already on them?

Did you not have an option in your client PCs' IP settings for DNS? If not, did the client PCs have a hardcoded DNS server already on them?
 
---------------------
 
Well, they did have an option for DNS but it was set to 'find automatically'. It had no problem finding it until yesterday and today.
 
Why would I have to hardcode the DNS to the DHCP server's IP address? Would it not find the DNS automatically with no problem?
 
 
Will Howard

Under the scope (IP range specific) or server (default settings for all scopes) options in DHCP, you *must* have your DNS server IPs in there so it can provide this information to your clients. On the client settings, the DNS entry can be left blank (where it reads "Obtain DNS server address automatically". That is how it is supposed to be setup. Is this combination how it was setup, and is no longer working? Or, have you now arrived at this combination from a previous configuration? When you state "hardcode the DNS to the DHCP server's IP address", it reads as if you are just now entering the DNS server's IP into your DHCP scope, which is how it should have been done all along.

I have had the DNS address in the DHCP's settings all along. I'm talking about on the clients computer's settings.
 
I have to hardcode the internal IP for the DHCP server into the DNS settings for the client. It used to be Obtain DNS Auto, but I had to change it because the Internet connection started going haywire.
 
Why would doing this to a clients computer even do anything? It should find all of this information automatically.
 
Thanks for the help,
Will Howard

OK, so to summarise:
 
You have DHCP and DNS running on one server
DHCP scope includes an entry for DNS, which points to the DNS server (which just happens to be the same machine as the DHCP server)
Suddenly, machines which lease addresses from the DHCP server are no longer able to access the internet because they're not picking up the DNS record
 
Right?
 
So, on one of the machines that can't see the internet, what happens if you type [font:courier]ipconfig from a command prompt?
 
Does the IP address and subnet match what the DHCP server should be providing? Or does the IP address start with 169? If that's the case, it means that the machine hasn't been able to get a new lease from the DHCP server, part of which will include the DNS server details.
 
It could be that your DHCP server has stopped working - check the server logs. Can you also see on the server what addresses are currently leased?
 
Just a couple of pointers
Rgds
AndyF

In the tradition of "Family Feud":
 
Good Answer! Good Answer! And the survey says...
 
Andy's on to something, as that is strong possibility. It could be that your clients aren't receiving IP information anymore. It might be the server, it could also be the network.