Question : DNS/DHCP sudden, random failures with no errors in logs

About 2 weeks ago our DNS/DHCP server suddenly stopped giving out IP addresses, but no errors showed up in any logs.  Restarting the DNS and DHCP services did not help, and the only thing that worked was a restart.  I tried to install a second dc to help with dns/dhcp fault tolerance, but now that one will not give out addresses at all.  Aside from the second DC not working, my biggest problem is that the first (and unchanged) dc has been suddenly stopping on a daily basis at random times.  I ran a diagnostic I found on a previous question here and the results are:

DC: W6023-1.mydomain.com
            Domain: mydomain.com

                 
               TEST: Authentication (Auth)
                  Authentication test: Successfully completed
                 
               TEST: Basic (Basc)
                   Microsoft(R) Windows(R) Server 2003, Standard Edition (Service Pack level: 1.0) is supported
                  NETLOGON service is running
                  kdc service is running
                  DNSCACHE service is running
                  DNS service is running
                  DC is a DNS server
                  Network adapters information:
                  Adapter [00000001] Intel(R) PRO/1000 MT Network Connection:
                     MAC address is 00:11:43:EB:CC:12
                     IP address is static
                     IP address: 192.168.1.4
                     DNS servers:
                        Warning: 192.168.1.9 (lis01.mydomain.com.) [Invalid]
                        Warning: 192.168.1.4 (w6023-1.mydomain.com.) [Invalid]
                  Error: all DNS servers are invalid
                  The A record for this DC was found
                  The SOA record for the Active Directory zone was found
                  The Active Directory zone on this DC/DNS server was found (primary)
                  Root zone on this DC/DNS server was not found
                 
               TEST: Forwarders/Root hints (Forw)
                  Recursion is enabled
                  Forwarders Information:
                     65.32.1.65 () [Valid]
                     65.32.1.70 () [Valid]
                 
               TEST: Delegations (Del)
                  Delegation information for the zone: mydomain.com.
                     Delegated domain name: _msdcs.mydomain.com.
                        Error: DNS server: lis01.mydomain.com. IP:192.168.1.9 [Broken delegation]
                        Error: DNS server: w6023-1.mydomain. IP:192.168.1.4 [Broken delegation]


These results repeat for the second DC as well.  I have no idea what could be wrong here since DNS is probably my weakest point.  

Answer : DNS/DHCP sudden, random failures with no errors in logs

Did you run the ipconfig /flushdns? '

Have you rebooted the server?

That is the problem. Delete any records of the old DNS server.