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Hi I have an existing and new server that are part of a windows domain. I want to redirect network traffic to the new server and keep the existing one online short-term then offline it after a few weeks. There will be no IP changes of hosts, and I cannot re-name my existing Server001 to reboot with a new name like Server001-OLD... but I am hoping I can rename it at dns level??

This is for a MS SQL DB server and contains Shared Folders accessed via UNC path. An ETL Server will access shared folders and the SQL Server DB based on host name "Server001" My goal is to allow connections to route to the new server(serverP1) using the existing server name (Server001) without changes and any 3rd Party software also continues to run (e.g. backup software)

For example: An older server, called Server001 (10.10.10.1) and a new one called ServerP1 (10.10.15.1)

Will this work successfully:

Can I request my DNS guys to update DNS:
Server001 to Server001-old (retaining current IP 10.10.10.1) hoping this will stop traffic going to old server

Create a new DNS entry CNAME /alias named Server001 referencing ServerP1 (10.10.15.1)

Thanks for any help!

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  • Do you use Kerberos authentication? MSSQL SPNs will still exist for that old host in active directory Nov 18, 2017 at 4:21
  • Thanks Jacob for asking/pointing out!:<P> We are not - but it was something I am thinking of doing in the future. There is no SPN on "Server001" (The existing host)<P> On the new machine (ServerP1) <P> Would the following work? (I don't know AD and if it will be successful .. in particular the first line) setspn -s MSSQLSvc/server001.mydoman.com\SQLServiceAccount setspn -s MSSQLSvc/serverP1.mydoman.com\SQLServiceAccount
    – slackstate
    Nov 20, 2017 at 0:06
  • You don't need SPNs for cnames Nov 20, 2017 at 0:07
  • Thanks for sharing that! (noted no spn for cnames needed) - Jacob does what I state for my question make sense, and would it be successful for my "Migration" or is the registered name for existing host (Server001) going to cause issues? .. is there some issue with Windows "WINS SERVER" registration for host names vs DNS names ?
    – slackstate
    Nov 20, 2017 at 0:08

1 Answer 1

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This is totally possible if you are okay with turning off the old server during the migration and leaving it off. If turning off the server is not an option then I would suggest looking into the SQL Client Alias (cliconfg) and redirecting the client machines, since the old server being online will require a DNS A record to work. Renaming the old server is really the best option here to free up the A record.

You could use a process like the one below to migrate the data and then redirect the clients using DNS. To reduce the outage you could use database mirroring to replicate the databases ahead of time, then just failvoer to the new instance and remove mirroring to cut over. If your backups take a long time this option is worth looking at.

  • Install new isntance on new server with same instance name
  • Backup database, logins, jobs, etc
  • Shutdown old server (begin outage)
  • delete DNS A record for old server
  • create new DNS CNAME record for old server name that points to new server name
  • Restore instance objects to new server (once complete outage over)
  • restart applications
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  • Thanks Jason! If I am reading your response correctly what I'm proposing should work? Thanks for suggestions on SQL Server. I have a ton of parts for SQL :( Setup, configure, jobs, shared folders ,etc Unfortunately no mirroring .. I do have a window. I'll perform a dif restore of the DBs, have fulls already there to save time during the actual date. I also have a webserver.. conceptually same question for my SQL Server for DNS, changing host name of old server. Making CNAME (alias) out of the old server name which will point to the new server.
    – slackstate
    Nov 22, 2017 at 1:29

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