[dns-operations] Root-servers returning TC=1 after 5 NXDOMAINS

Matthew Pounsett matt at conundrum.com
Tue Feb 10 14:26:34 UTC 2015

On Feb 10, 2015, at 09:06 , Emil Natan <shlyoko at gmail.com> wrote:

> If this is an issue with the F-root only it would be easier to use hints file with the F excluded instead of managing local root zone and keeping it up to date.

This is Response Rate Limiting in action… they’re not explicitly limiting NXDOMAIN responses; they’re limiting identical responses.  If Bert’s server was asking for the same A record over and over that would get truncated and forced over to TCP as well.   It’s probably not only F, although I don’t think I’ve seen a comprehensive list of which root instances are running RRL.  

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