WAN migration to new Internet - DNS concerns

[Steve Coady]

Hello

My compnay is in the process of migrating to a new internet soltuion

New ISP's

New External facing ip addresses.

How can I prepare my DNS for this new solution?

[ghostinthenet · Accepted solution]

If you're referring to your external DNS, I would reduce the time-to-live (TTL) on the zones to a very small value (5 minutes is good) 24 hours prior to the move. This way you've done your best to ensure that the old values don't stay in any caches after the move. Once you've done the move, update the DNS zones to use the new IP addresses and restore the old TTL value. That should do it.

[Steve Coady]

Jody

Thank you for the response. My apologies for the delay.

A little back ground

Our current ISP is also our DNS provider. This ISP HE router has static routes back into our network for the external ip address subnet used for DNS

When we move to the new ISP links, we plan on keeping the same DNS provider, for now.

This complicates things and I am not sure what the best solution would be. any guidance would be appreciated.

[ghostinthenet · Accepted solution]

The low TTL should work for the initial move then. When you're ready to switch your DNS somewhere else, you can set it up as a secondary and then promote it to primary when you're ready to retire the original. That's something you do well after the move of you're planning on keepin the original DNS for a bit.

[Steve Coady]

Jody

I guess where I am confused is:

Will I need my current ISP/DNS provider to make any changes in their DNS or their  routing to assure getting back to me across the new links?

[ghostinthenet]

If you're keeping the same IP addresses for the new links, they'll need to change the routing. For new addresses, they'll only need to change DNS.

[Steve Coady]

Jody

That is the issue. How to migrate my current external facing devices to a new WAN link and not cause any routing issues.

Thanks for the guidance.

[ghostinthenet]

Okay, if everything is moving to a new WAN link with different IP addresses, then you don't need to worry about th routing. Just lower the TTL on the DNS zone 24 hours before the move, make the changes when you do the cutover and then restore the TTL. That makes for minimal downtime.