TWTelecom DNS issues...

Wil Schultz wschultz at
Wed Mar 2 21:09:06 CST 2011

On Mar 2, 2011, at 6:31 PM, Jay Ashworth wrote:

> ----- Original Message -----
>> From: "Christopher Morrow" <morrowc.lists at>
>> On Wed, Mar 2, 2011 at 1:38 PM, Wil Schultz <wschultz at>
>> wrote:
>>> and (along with some other DNS
>>> servers, and suddenly
>>> stopped serving DNS for domains it's not authoritative for this
>>> morning. Requests are being actively refused from within their
>>> network.
>>> Caused a small issue for us, just thought I'd pass along.
>> they were recursing previously and are no longer? that seems like a
>> win... or did I misconstrue what you said?
> Not if you're an end user who was configured, for some reason, to use them
> as a recursive server... which is what I infer from the fact that he posted 
> it.  In which case, it would be useful for Wil to provide us the IP
> addresses of those servers as he understand them, since that is what such
> affected users would have programmed...
> Cheers,
> -- jra

Oh sure, here are the ones that I tested and can confirm were down. Well, not "down" but actively refusing queries. ( ( ( ( (, 2001:4870:6082:3::5) (, 2001:4870:8000:3::5) and are well known to be authoritative for a number of domain, and I would have presumed that the rest would be their recursive servers. I found an old welcome letter from them that states and were the preferred forwarders on the circuit.

Some other network segments use their other resolvers but weren't affected because our internal boxes cache. I can't speak as to why they have it set up this way, but that's the list I have and every single one wasn't working from within or outside of their network. From my testing authoritative requests were never denied, however.

There was a complete outage for a bit over an hour, then it was intermittent for a couple hours after that. Also, good or bad, all of the above servers recurse from on and off their network once again. Their NOC gave me a resolution of "Added an ACL to block an IP address". :-)

Regardless, I'm not using their resolvers anymore but thought it would be helpful in case anyone else saw a segment of their network start yammering about facebook and twitter being down.


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