Hi all, I have a fairly major issue going right now and I was wondering if you had opinions on where the problem lies. We have a child domain here, with it's own DC and exchange server. Parent domain and master exchange servers are in the UK. Currently, all email outbound is queuing due to being unable to contact the master servers (which are located in the UK - all email goes in and out via them). Checking the exchange server, it's reporting 'destination server does not exist' for the master server. Tools/Monitoring and Status/Status shows both mine and the master server as unreachable. Here is where it gets funky. My DC runs a DNS server. It resolves all domain traffic over an MPLS link and all other traffic over our ADSL. However, it looks like there is something iffy with the DNS resolution. All normal DNS is working, ie web browsing. Exchange server is online locally and we can get each others emails, just nothing in or out from the outside world. DCDIAG reports: Starting test: Connectivity The host <guid>._msdcs.parentdomain.com could not be resolved to an IP address. Check the DNS server, DHCP, server name, etc Although the Guid DNS name (<guid>._msdcs.parentdomain.com) couldn't be resolved, the server name (dc.localdomain.parentdomain.com) resolved to the IP address (192.168.191.6) and was pingable. Check that the IP address is registered correctly with the DNS server. and... TEST: Basic (Basc) Error: No LDAP connectivity Warning: adapter  HP NC373i Multifunction Gigabit Server Adapter has invalid DNS server: 192.168.191.6 (<name unavailable>) Warning: adapter  HP NC373i Multifunction Gigabit Server Adapter has invalid DNS server: 192.168.191.254 (<name unavailable>) Error: all DNS servers are invalid Error: The A record for this DC was not found Netdiag also reports: Testing the WINS server Local Area Connection Sending name query to primary WINS server 192.168.191.6 - Passed There is no secondary WINS server defined for this adapter. Gathering Winsock information. Testing DNS [WARNING] The DNS entries for this DC cannot be verified right now on DNS server 192.168.191.6, ERROR_TIMEOUT. [WARNING] The DNS entries for this DC are not registered correctly on DNS server '192.168.191.254'. Please wait for 30 minutes for DNS server replication. [FATAL] No DNS servers have the DNS records for this DC registered. I also have messages in the event log about failed domain replication (NTDS KCC, error 1925), DNS (error 113, dns server could not signal the service 'NAT'). Now, does this point to an issue with the parent domain controllers, or my unit? I've gone through every possible fix I can find for these issues individually, but nothing seems to get the DNS up to a state that passes dcdiag. Any and all comments are welcome.