• Were adding a 2nd link from our ISP to our network.
  • We newly acquired our own IP block from RIPE
  • In the same stride, we plan to replace our external BIND DNS servers with windows DNS servers.
  • Once the DNS switch is done, we will migrate each service in a controlled fashion to the new IP Block
  • The BIND dns servers are on the same subnet, where as the new WIN dns servers will each be in a different subnet.

DNS Servers: Bind DNS ("BIN" dns): ns1.zone.com ns2.zone.com

Win DNS ("WIN" dns): ns3.zone.com ns4.zone.com

Current status for WIN NS3 & NS4

  • not registered by the Registrar
  • not accessible to public internet
  • All zones have been copied from BIN to Win dns servers

The Plan:

Step 1

  • Set TTL to 5 mins on both sets of DNS servers (WIN, BIN)
  • Register WIN dns servers at registrar

Step 2

  • Add RR for WIN to BIN dns servers and vice versa

  • Wait for propgoation (3-4 days)

  • Test that WIN dns servers are available to the public and are resolving IP's correctly

  • Reset TTL values to default

  • Remove BIN dns server registration (or can i just shut them off temp. incase I need to rollback)

  • shutdown bin DNS servers


  • What mistakes am I making here?
  • How can this be done better?
  • What happens when a nameserver is added to the registrar, but remains unreachable?

Say I have 4 registered nameservers, of which the 4th one is not available. Will the DNS client query the next registered nameserver? Or just fail permanently.


In this scenario since all 4 DNS servers contain the same records, the easiest way to do this is:

  1. Login to the registrar, and simply replace the old (BinDNS) authorative nameservers with the new ones (WinDNS).
  2. Make sure you keep your old (BinDNS) DNS servers running until propagation is complete.

Keep in mind that propagation will be TTL+refresh because if your local server hits Name Servers other than Authoritative Name Server it might still get the non-refreshed records. source: http://hosting.intermedia.net/support/kb/?id=797

Therefore make sure you keep your old (BinDNS) servers online until your certain propagation has completed.

You can use https://www.whatsmydns.net/ to check propagation.

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