Scenario:
- 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
Questions:
- 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.