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DNS question

Posted on 2013-11-27
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Last Modified: 2013-12-03
If we have a secondary dns that goes offline, shouldnt it round robin back to the primary dns? It seems our secondary DNS crashed and after that we were getting DNS issues. Could it be the request round robin'ed back to the primary but timed out by that time? Thanks
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Question by:Thomas N
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by:Chris Millard
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Your client machines ned to be aware of the other DNS server. DHCP should be handing out primary and secondary DNS details to your clients. If the client cannot contact the primary DNS server, it will contact the secondary.
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by:Thomas Grassi
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make sure your computers can ping the dns server using fqdn

A test would be to stop the DNS services on one and see if it works
Then stop dns on the other and see if they still work.

nslookup would also be a good tool to use for this
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by:Thomas N
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Can the primary DNS be inundated with requests and go to the secondary, then if the secondary is offline it will time out. Is that a possibility? Im just trying to figure out why the requests are timing out even if the secondary goes down.
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by:Thomas Grassi
Thomas Grassi earned 250 total points
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What DNS errors are you getting? Have you check the DNS event log?
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by:Thomas N
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Machines just cant resolve names but they can by IP. Some machines when we do a nslookup we get the error below.

The DNS server (165.) that is being used for VPN is having issues again:
c:\>nslookup outlook.com
Server:  .net
Address:  165.
 
DNS request timed out.
    timeout was 2 seconds.
DNS request timed out.
    timeout was 2 seconds.
DNS request timed out.
    timeout was 2 seconds.
DNS request timed out.
    timeout was 2 seconds.
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by:Thomas N
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Also nothing in the DNS logs
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by:Thomas Grassi
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What OS are the Server?

run this on them

@echo off
dcdiag >dclogx.txt
dcdiag /test:registerindns /dnsdomain:FQDM>>dclogx.txt
dcdiag /c /v >>dclogx.txt
dcdiag /test:dns >>dclogx.txt
exit

Post results
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by:Thomas N
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2008 server. Am I suppose to create a bat or vbs script with the commands you gave, then run it? Or am I suppose to do it at the command prompt?
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by:Thomas Grassi
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Thomas

My name is Thomas also

Yes you can run them from a command prompt.

I just create a dctest.cmd file

I run this on  my servers weekly  just a thought
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by:Thomas N
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Thanks for your help Thomas!

How long does it run for? I created a cmd file and it pulls up a blank DOS screen and stays there.
dns.png
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by:Thomas Grassi
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It does not run long

Make sure you have dcdiag on your servers.

It comes with the support tools from Windows 2003 server

http://www.microsoft.com/en-us/download/details.aspx?id=15326
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by:Thomas N
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I have it on the server. I used dcdiag on it before. I just did each one individually.

Strange, when I run the line "dcdiag /c /v >>dclogx.txt" and "dcdiag /test:dns >>dclogx.txt" it hangs. The other 2 I have attached the log files.
dclogx.txt
dclog.txt
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by:Thomas N
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I tried to run the command without sending it to the log file. This is what I get.

Z:\>dcdiag /test:dns

Directory Server Diagnosis

Performing initial setup:
   Trying to find home server...
   Home Server = server
   * Identified AD Forest.
   Done gathering initial info.

Doing initial required tests

   Testing server: TXSDC\server
      Starting test: Connectivity
         ......................... server passed test Connectivity

Doing primary tests

   Testing server: TXSDC\server

      Starting test: DNS

         DNS Tests are running and not hung. Please wait a few minutes...
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by:Thomas Grassi
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They look ok

But you have many system event log errors. Some we need to review.

the dcdiag /test:dns hangs not good

I found this take a look

http://social.technet.microsoft.com/Forums/windowsserver/en-US/eeddc6f7-c603-4f1a-9340-f783e1077d59/dcdiag-fix?forum=winserverDS
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by:Thomas Grassi
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Do you have IPV6 enabled on the network adapters for these Servers?

Disable all IPV6.

Check thru all your DNS records A Records Pointer Records and make sure the servers all have the correct Ip address and make sure no servers are registering IPV6 in the dns.
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Sandeshdubey earned 250 total points
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Starting test: Replications

         REPLICATION-RECEIVED LATENCY WARNING

         IEPSZW002:  Current time is 2013-11-27 11:13:26.

            DC=ForestDnsZones,DC=txaccess,DC=net
               Last replication received from PWZW007 at
          2013-05-21 11:21:58
               WARNING:  This latency is over the Tombstone Lifetime of 180

         days!

               Last replication received from VZD001 at
          2013-05-21 11:32:53
               WARNING:  This latency is over the Tombstone Lifetime of 180

         days!

               Last replication received from VZR032 at
          2013-05-21 11:14:55
               WARNING:  This latency is over the Tombstone Lifetime of 180

         days!

            DC=DomainDnsZones,DC=txaccess,DC=net
               Last replication received from PWZW007 at
          2013-05-21 11:21:59
               WARNING:  This latency is over the Tombstone Lifetime of 180

         days!

               Last replication received from VZD001 at
          2013-05-21 11:32:53
               WARNING:  This latency is over the Tombstone Lifetime of 180

         days!

               Last replication received from VZR032 at
          2013-05-21 11:14:55
               WARNING:  This latency is over the Tombstone Lifetime of 180

         days!

            CN=Schema,CN=Configuration,DC=txaccess,DC=net
               Last replication received from PWZW007 at
          2013-05-21 11:21:58
               WARNING:  This latency is over the Tombstone Lifetime of 180

         days!

               Last replication received from VZD001 at
          2013-05-21 11:32:52
               WARNING:  This latency is over the Tombstone Lifetime of 180

         days!

               Last replication received from VZR032 at
          2013-05-21 11:14:55
               WARNING:  This latency is over the Tombstone Lifetime of 180

         days!

            CN=Configuration,DC=txaccess,DC=net
               Last replication received from PWZW007 at
          2013-05-21 11:21:58
               WARNING:  This latency is over the Tombstone Lifetime of 180

         days!

               Last replication received from VZD001 at
          2013-05-21 11:32:52
               WARNING:  This latency is over the Tombstone Lifetime of 180

         days!

               Last replication received from VZR032 at
          2013-05-21 11:14:54
               WARNING:  This latency is over the Tombstone Lifetime of 180

         days!

            DC=txaccess,DC=net
               Last replication received from PWZW007 at
          2013-05-21 11:21:57
               WARNING:  This latency is over the Tombstone Lifetime of 180

         days!

               Last replication received from VZD001 at
          2013-05-21 11:32:53
               WARNING:  This latency is over the Tombstone Lifetime of 180

         days!

               Last replication received from VZR032 at
          2013-05-21 11:14:54
               WARNING:  This latency is over the Tombstone Lifetime of 180

The above log indicates that you have replication issue between DCs and the server has reached tombstone lifecycle period.

As the Server has reached the tombstone lifecycle period.To fix the issue you need to demote and promote the server.You cannot demote the faulty DC gracefully you need to do forcefull removal.You need to ran dcpromo/force removal and then run matadata cleanup on other DC(healthy) to remove the instance of faulty DC from AD database and DNS.If faulty DC is fsmo role holder server the you need to seize the FSMO role on other DC.

Once done you can promote the Server back as ADC.Also configure authorative time server role on PDC role holder server.

Reference link
Forcefull removal of DC: http://support.microsoft.com/kb/332199
Metadata cleanup: http://www.petri.co.il/delete_failed_dcs_from_ad.htm
Seize FSMO role: http://www.petri.co.il/seizing_fsmo_roles.htm
Authorative time server: http://support.microsoft.com/kb/816042
Configuring the time service on the PDC Emulator FSMO role holder

You need to first fix replication issue between DC.Also ensure correct dns setting on DCs and client as this:http://abhijitw.wordpress.com/2012/03/03/best-practices-for-dns-client-settings-on-domain-controller/
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