On 2013-09-11, at 11:50 PM, Paul Vixie <p...@redbarn.org> wrote: >>> "A DNS UDP responder shall, when transmitting a message which does not >>> include embedded cryptographic marks such as TSIG or DNSSEC signatures, use >>> an effective DNS message payload size which is calculated as MIN(OFFERED, >>> MIN(DISCOVERED, ESTIMATED) - OVERHEAD)) where OFFERED is the EDNS BUFSIZE >>> received from the initiator, and DISCOVERED is the path MTU if known or >>> else the outbound interface MTU, and ESTIMATED is chosen as 576 for IPv4 or >>> 1280 for IPv6 as the minimum guaranteed size of an IP datagram, and >>> OVERHEAD is chosen as 64 for IPv4 or 48 for IPv6 as the maximum likely size >>> of the IP and UDP headers. >> >> Shouldn't OVERHEAD actually be 68 for IPv4? > > i am counting 40 for the ipv6 header and 8 for the udp header. where are you > getting your 68 number from?
48 is correct for IPv6. But max IPv4 header size is 60 bytes, plus 8 for UDP is 68. -Aaron _______________________________________________ dns-operations mailing list dns-operations@lists.dns-oarc.net https://lists.dns-oarc.net/mailman/listinfo/dns-operations dns-jobs mailing list https://lists.dns-oarc.net/mailman/listinfo/dns-jobs
