Redundant ISP and DNS
Posted on 2010-09-21
We have two ISP's coming into our facility. We have two external DNS servers we host onsite, one being on one ISP and one on the other. Network Solutions holds the records pointing the names of these servers to the respective ISP IP address.
What I want to get in place is some type of DNS redundancy if one ISP goes down. Right now I have DNS1 hosting A records for our internal devices pointing to IP's from ISP1. And DNS2 hosting A records for our internal devices pointing to IP's from ISP2. Via NAT, I'm pointing the appropriate ISP IP's, whether from ISP1 or ISP2 to the same internal IP on our internal network.
This all works fine, I can ping from outside and see that it resolves to both IP's, normally about 50% one and 50% the other. The issue is is one ISP goes down then the corresponding DNS server is not available. So users on the outside get bad lookups about 50% of the time. They have no way of knowing that particular DNS server is down and since Network Solutions still holds the record, outside users can still make requests to it.
I'm wondering how I could have better results. Is there something Network Solutions could do to monitor the health of the two records they hold for our DNS servers? will Registrars do that and adjust the requests accordingly? Or is there some other record manipulation I could do myself to help.
thanks for any insight into what others are doing for DNS redundancy.