MadPPC

A couple days ago all of a sudden I couldn’t access my email accounts on a server of mine.  I figured it was most likely temporary, who knows – shit happens – and sometimes the tubes get crossed.  However after a day I was getting pretty concerned.

I wondered why, after months of no issues, all of a sudden none of my domains using that nameserver resolved.  As it turned out the solution was pretty simple, but very unexpected.

The answer was: my private nameserver wasn’t returning ‘A records‘.  Yeah, I know right?  WTF.

The reason why nameservers now have to return ‘A records‘ is to prevent whats called ‘DNS cache poisoning‘.  In layman explanation would be, basically it prevents someone from making you connect to a server it shouldn’t.  That’s probably not the best explanation ever, but you can read up more on it through the link I posted.

How do you fix it when it happens?

You have to give your nameservers ‘A records‘.  So for example in this instance my own server runs it’s own DNS server, I just add my nameserver domain like I would with any other domain.  I then at the registrar set the nameservers of my nameserver domain to itself (ns1./ns2.domain-server.tld)  because it already points to the server running the DNS server.  Reading that it sounds really confusing, but all your doing is adding nameservers to a domain like you would with any other domain.

That’s all that’s to it.