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RodH257
Asked: 2011-01-20 21:58:15 +0800 CST

DNS doesn't match DHCP correctly

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I'm a programmer who is tasked with handling server support until we can hire a new sysadmin, so bear with me. I'm having a problem, where the DNS records for computer names don't resolve to the correct IP.

For example computer name RODSCOMPUTER's actual IP address (from DHCP in Server 2008 R2, also confirmed on ipconfig) is 192.168.1.111 however when I go on another machine and ping RODSCOMPUTER it resolves to 192.168.1.149. Also when I go to the DNS management console in Server 2008 R2 it shows up as the wrong value.

I take it it's expired, but DNS hasn't caught up - how do I make this stay accurate? It's vital for us in our network as we remote desktop frequently.

domain-name-system dhcp windows-server-2008-r2

2 Answers

  1. For a quick fix, try running this on the client computer:

    ipconfig /registerdns

    This should update the DNS record for this client.

    Also, you might want to take a look at this document which explains how to configure Dynamic DNS Updates on Windows Server 2003 (We don't have Server 2008 R2, so I can't tell if it applies to you - but I don't think it will be all too different).

    http://support.microsoft.com/kb/816592

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  2. the command is ipconfig /flushdns not /registerdns You need to to clear the dns cache first so then you can query the DNS server directly. On MS windows, the order of operation for DNS is : 1. hostfile 2. dns cache 3. dns server

    You have this issue because 3 reasons: 1.Your TTL time for the records are to big. make them smaller like 5-12 hours. 2.You are allowing Dynamic Updates 3.Your DHCP lease time is to small

    DNS TTL tels the client how long the record is valid. Based on this value its cache in the local dns cache.

    Dynamic Updates: Every time you serve DHCP, the windows client updates its record in DNS (you can mitigate the Dynamic Updates if you chose register dns and append suffixes in the Network Connection of the Adapter on the workstation)

    I figured that you DHCP lease time is to small by the fact that you have so many changes in the DNS that would cause problems.

    Here is a good article for you:

    http://support.microsoft.com/kb/297510

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