[dns-operations] Strange problem with fragmented DNS responses from b.iana-servers.net

[Robert Edmonds]

Duane Wessels wrote:
> The folks at ICANN ran tcpdump on the server and we saw both fragments
> leave the server.
> 
> So far the problem seems localized to ISC's network, but we are at
> a loss to explain what could be causing it.  ISC tells me they have
> no packet filters on their peer/transit provider links.
> 
> I'm really curious if anyone else sees this problem from their own
> networks or not.

the only difference i see is in the last few hops:

traceroute from a (working) speakeasy-connected host:

[...]
10  ae-2.ebr2.Amsterdam1.Level3.net (4.69.132.134) [AS3356]  137.515 ms
11  ae-22-52.car2.Amsterdam1.Level3.net (4.68.120.48) [AS3356]  181.529 ms
12  *
13  gw.tri.nikrtr.ripe.net (193.0.0.145) [AS3333]  143.513 ms
14  b.iana-servers.net (193.0.0.236) [AS3333]  141.543 ms !X

traceroute from a (non-working) ISC-connected host:

[...]
11  ae-2.ebr2.Amsterdam1.Level3.net (4.69.132.134) [AS3356]  151.938 ms
12  ae-22-54.car2.Amsterdam1.Level3.net (4.68.120.112) [AS3356]  148.881 ms
13  gw.amsix.telrtr.ripe.net (195.69.144.71) [AS1200]  160.255 ms
14  gw.tri.nikrtr.ripe.net (193.0.0.145) [AS3333]  160.150 ms
15  b.iana-servers.net (193.0.0.236) [AS3333]  159.643 ms !X

-- 
Robert Edmonds
edmonds at gtisc.gatech.edu