Self Hosting and Self DNS Single Point of Failure?

Question by Steven C: Self Hosting and Self DNS Single Point of Failure?
I know it is recommended that DNS be hosted on two separate servers to prevent a single point of failure, when the DNS server is the same as the hosting server, the logic doesn’t make sense in my head.

currently, I am pointing both hostnames ns1 and ns2 to the same server ip xxx.xxx.xxx.xxx. The nameserver is only serving domains on that are hosted on the same server xxx.xxx.xxx.xxx. I set it up this way because I have a Cloud VPS with ISPConfig 3 and I want to be able to manage the hosting and dns all on the same server. So basically the logic is..

dns1, dns2, and website on same server, so either all up or all down
DNS1 up DNS2 up SERVER up = Website Up
DNS1 down DNS2 down SERVER down = Website Down

If I were to setup DNS2 on a different server, then it would be pointless.. if DNS1 went down, DNS2 would report the IP to the server.. but since DNS1 is down, so would the website.. meaning the page still wouldnt be brought up… so DNS2 is practically useless.. because when the website comes back up, so would DNS1.. and DNS2 would not be needed again.
brisray –
I would think that having DNS in a separate location would ADD a point of failure..

Webserver Is Up – DNS Is Up With It — Website is working!
Webserver Goes Down – DNS Goes Down With It — oh well, DNS isn’t needed the server’s down anyway, no use in pointing to a down webserver.

Website is up – DNS Is Up — Site is working!
Website is up – DNS Goes Down — My webserver is working, but nobody can get to it . .

Best answer:

Answer by brisray
The point of having multiple name servers is to provide redundancy. Name servers shouldn’t be anywhere near each other, preferable they should be in different states/countries.

By putting your file server and primary name server on the same computer you’ve provided a single point of possible failure so you may as well not bother with the second name server.

It’s a bit like having two identical files file.doc and file_copy.doc in the same directory and thinking you’ve got adequate backups.

Know better? Leave your own answer in the comments!

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