DNS

Question

Hi All,

Today we are in the process of upgrading one of our Domain Controllers. It was switched off last week for 4 hours in order for us to establish whether there was anything pinned to the DC. There were no comebacks and so we continued with the demotion this a.m.

After a short while into the demotion customers complained that they were unable to access a certain application. This application was on a server that was pinned to the DC that we demoted, however, there was another DC that it should have failed over to.

Does anyone know how we can check as to whether the failover has worked correctly as we would not like to see this situation occur with the remainder of the servers we intend to upgrade.

Any information would be useful.

Regards.

Answer 1

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Answer 2

Hello czql5v,

Thank you for your reply.

You can try to check the DNS server under "Applications and Services Logs".

For example:

If you have any question or concern, please feel free to let us know.

Best Regards,
Daisy Zhou

Answer 3

Hi Daisy,

Thanks for the information, i will check and report back but I think the ping checks were already made and successful using IP address and host.

I just wondered if there were any logs I could check on the app server that might give me some kind of indication of what might have gone wrong at that particular time.

Regards.

Answer 4

Hello czql5v,

Thank you for posting in Microsoft Community forum.

After a short while into the demotion customers complained that they were unable to access a certain application. This application was on a server that was pinned to the DC that we demoted, however, there was another DC that it should have failed over to.
A: Please check the DNS server on the server with this application, please keep the IP address of another DC and its own IP address of this DC (if it is also one DNS server) under Use the following DNS server address, remove the IP address of the DC you demoted from here.

Does anyone know how we can check as to whether the failover has worked correctly？
A: On **the server with this application, can you ping domain name (ping domain name) and FQDN of another DC (ping anotherDC.domain.com)?**Also, consider the following:

• If the removed domain controller was a global catalog server, evaluate whether application servers that pointed to the offline global catalog server must be pointed to a live global catalog server.
• If the removed DC was a global catalog server, evaluate whether an additional global catalog must be promoted to the address site, the domain, or the forest global catalog load.
• If the removed DC was a Flexible Single Master Operation (FSMO) role holder, relocate those roles to a live DC.
• If the removed DC was a DNS server, update the DNS client configuration on all member workstations, member servers, and other DCs that might have used this DNS server for name resolution. If it is required, modify the DHCP scope to reflect the removal of the DNS server.
• If the removed DC was a DNS server, update the Forwarder settings and the Delegation settings on any other DNS servers that might have pointed to the removed DC for name resolution.

I hope the information above is helpful.

If you have any question or concern, please feel free to let us know.

Best Regards,
Daisy Zhou