In message <4bdf39f7.1060...@ou.edu>, Peter Laws writes: > On 05/03/10 15:55, Lightner, Jeff wrote: > > > > Also one of the links I sent earlier had a similar comment about less > > than 300 bytes difference not being a problem. I had missed that. > > > > 4096 - 3843 = 153 > > It seems if I'd paid attention I'd not have posted my follow up > > questions. > > It's not on the dns-oarc.net page either, but I'm glad you mentioned it. > > Back to explicitly setting edns-udp-size to something smaller than the > default, which seems to be 4096. Still not convinced this is necessary.
The test is a rough guide to the maximum packet size supported by the path. The usual break points are ~2048 (old nameservers used as forwarders, forwarding through a DNS proxy w/ a 2K UDP buffer), ~1500 (IPv4, IPv6 fragments being dropped), ~1200 (IPv6 fragments being dropped), and 512 (firewalls dropping DNS responses > 512). A NAT/firewall that doesn't handle out of order fragments can produce results all over the place. Mark > -- > Peter Laws / N5UWY > National Weather Center / Network Operations Center > University of Oklahoma Information Technology > pl...@ou.edu > ----------------------------------------------------------------------- > Feedback? Contact my director, Craig Cochell, cra...@ou.edu. Thank you! > _______________________________________________ > bind-users mailing list > bind-users@lists.isc.org > https://lists.isc.org/mailman/listinfo/bind-users -- Mark Andrews, ISC 1 Seymour St., Dundas Valley, NSW 2117, Australia PHONE: +61 2 9871 4742 INTERNET: ma...@isc.org _______________________________________________ bind-users mailing list bind-users@lists.isc.org https://lists.isc.org/mailman/listinfo/bind-users
