nanog mailing list archives
Re: DNS pulling BGP routes?
From: Masataka Ohta <mohta () necom830 hpcl titech ac jp>
Date: Sat, 9 Oct 2021 17:37:09 +0900
Christopher Morrow wrote:
means their DNS servers were serving the zone, even after they recognize their zone data were too old, that is, expired.
that's not what this means. I think Mr. Petach previously described this,
He wrote:
So, the idea is that if the edge CDN node loses connectivity to the core datacenters, the DNS servers should stop answering queries for A records with the local CDN node's address, and let a different site respond back to the client's DNS request.
which may be performed by standard DNS with short expire period, after which name servers will return SERVFAIL and other name servers in other edge node with different IP addresses are tried. It may be that facebook uses all the four name server IP addresses in each edge node. But, it effectively kills essential redundancy of DNS to have two or more name servers (at separate locations) and the natural consequence is, as you can see, mass disaster.
but: 1) dns server in pop serves some content (ttls aren't important right now)
You MUST distinguish TTL and EXPIRE. They are different. > there's not a lot of magic here... and it's not about the zone data > really at all. Statement of Petach: "the edge CDN node loses connectivity to the core datacenters, the DNS servers should stop answering" means, with DNS terminology, zone data is expired, which has nothing to do with TTL. Masataka Ohta
Current thread:
- Re: DNS pulling BGP routes?, (continued)
- Re: DNS pulling BGP routes? William Herrin (Oct 07)
- Re: DNS pulling BGP routes? Masataka Ohta (Oct 07)
- Re: DNS pulling BGP routes? Sabri Berisha (Oct 07)
- Re: DNS pulling BGP routes? Mark Tinka (Oct 07)
- Re: DNS pulling BGP routes? Masataka Ohta (Oct 08)
- Re: DNS pulling BGP routes? Tom Beecher (Oct 08)
- Re: DNS pulling BGP routes? Carsten Bormann (Oct 08)
- Re: DNS pulling BGP routes? William Herrin (Oct 08)
- Re: DNS pulling BGP routes? Masataka Ohta (Oct 08)
- Re: DNS pulling BGP routes? Christopher Morrow (Oct 08)
- Re: DNS pulling BGP routes? Masataka Ohta (Oct 09)
- Re: DNS pulling BGP routes? Bill Woodcock (Oct 09)
- Re: DNS pulling BGP routes? Masataka Ohta (Oct 09)
- Re: DNS pulling BGP routes? Christopher Morrow (Oct 11)
- Re: DNS pulling BGP routes? Matthew Petach (Oct 11)
- Re: DNS pulling BGP routes? Masataka Ohta (Oct 12)
- Re: DNS pulling BGP routes? Matthew Petach (Oct 11)
- Re: DNS pulling BGP routes? Masataka Ohta (Oct 12)
- Re: DNS pulling BGP routes? Matthew Petach (Oct 12)
- Re: DNS pulling BGP routes? Masataka Ohta (Oct 13)
- Re: DNS pulling BGP routes? Tom Beecher (Oct 13)