[BlueOnyx:27380] Re: BlueOnyx not resolving

[Michael Stauber]

Hi Gregg,

> I take it back.  I just checked and it's not resolving again. Does the
> resolver pause itself if there is an attack? All I could think of is maybe
> someone is trying a DDOS and the resolver quits for a while, and starts back
> up? How can I trace this problem?

If you use external resolvers like this, then it's out of your hands. It 
either works, or doesn't. It could be that these external resolvers have 
rate limiting or some other checks and balances which limit or prevent 
your server from using them.

For testing purpose you can use this in the shell:

nslookup blueonx.it <IP of Resolver>

Example:

nslookup blueonyx.it 8.8.8.8

That would query the Google DNS server at the IP 8.8.8.8 for the IP of 
the domain blueonyx.it

When you test with the IP(s) of the resolvers you have configured 
instead of the 8.8.8.8 you can see what response a program would get 
when trying to use said resolver.

If you're using the DNS of your ISP or a public resolver? Then I'd try 
to switch it to something else just for testing. Like these:

8.8.8.8  (Google)
8.8.4.4  (Google)
1.1.1.1  (CloudFlare)

My personal preference is to not use those in production, but if you're 
in a bend and need to rule out that your own DNS resolver is borked? 
Then they're a good thing to test against.

-- 
With best regards

Michael Stauber