dns problems

Active Directory
Microsoft Windows
Networking services
I have a DC with Exchange 2003 on Server 2003. I am having some DNS problems which I belive is causing Outlook to Exchange connectivity issues. I understand that there should be a DNS entry _ldap._tcp.dc._mcdcs in the DNS. I did not have this and I tried to manually add it. I have it in the forward lookup zones. The only warning I get is in the application log: MSExchangeDSAccess event ids 2105 and 2106 every 15 min. Thank you for any help you can provide! When I type nslookup I get: *** Can't find server name for address Non-existent domain Default Server: UnKnown Address: When I type dcdiag I get this error: Testing server: Default-First-Site-NameBMZ-SERVER Starting test: Connectivity The host 43132910-dc4a-4cf3-9961-79807936892b._msdcs.hun.bmzlaw.com could not be resolved to an IP address. Check the DNS server, DHCP, server name, etc Although the Guid DNS name (43132910-dc4a-4cf3-9961-79807936892b._msdcs.hun.bmzlaw.com) couldn't be resolved, the server name (BMZ-SERVER.hun.bmzlaw.com) resolved to the IP address ( and was pingable. Check that the IP address is registered correctly with the DNS server. .......BMZ-SERVER failed test Connectivity

Answer Wiki

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Check www.eventid.net — 2106 reveals this possibility:


Comments Ionut Marin (Last update 3/25/2005):
From a newsgroup post: “My DNS settings were wrongly configured. The server?s NIC was pointing to external DNS rather than its own DNS server. After I fixed this issue, the problem disappeared”.

See M246175 for information on the role of DSAccess in an Exchange 2000 Server.


Good luck,


Discuss This Question: 4  Replies

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  • Amcdowell
    Platypus: I have checked and the NIC's DNS entry is pointing to its own IP address, which is the DNS server Thanks
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  • Studley
    If you have more then one domain controller running DNS services, set the exchange server to point to the other DC for DNS resolution.
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  • Cknets
    the _ldap._tcp.dc._mcdcs should be on the dns server which the workstation is using. 1. Make sure the workstation is pointing to dns that has the _ldap._tcp.dc._mcdcs zone 2. Make sure the dns zone is accepting dynamic update.
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  • Sonyfreek
    I'm not sure by your post if you also created a forward lookup zone for your domain. The _ldap._tcp. stuff is when clients and servers try to find services in the domain, such as a PDC emulator, Global Catalog, etc. You will also need to create the forward record for your AD domain. If your domain were named example.com, you would have to create an example.com forward lookup record. This is what nslookup uses when you try to locate an A record for a host. In the end, you should have at least two forward zones: "example.com" and _ldap._tcp. etc. The _ldap._tcp zone should populate itself with the services available in the domain and example.com will also do so if you allow it to have dynamic updates. Make sure you are running the service DHCPClient or your server will not automatically register it's DNS records (although with a domain controller, I believe it may not need to). I'd also recommend creating reverse lookup zones for all of your subnets. If you have a subnet, you would create it as a primary AD integrated zone (or at least a primary zone) and set the IP address of the first three octets. Windows dumbs down the user again by automagically reversing the IP address to the correct format of 69.16.192.in-addr.arpa. The reverse domain is useful for looking up IP Addresses when you don't know the hostname. Hope this helps, SF
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