On 2023-07-17 12:40 -04, "John Levine" <jo...@taugh.com> wrote: > It appears that Florian Obser <florian+i...@narrans.de> said: >>I gave this a once-over. >>3. Common Pitfalls >>> If the size of the response is large enough that it does not fit into >>> a single DNS UDP packet (UDP being the most common DNS transport >>> today), this may result in fragmentation >> >>That's not correct. If the response does not fit into a single DNS UDP >>packet, it's not a valid response and can't be send. >> >>New: If the size of the response is large enough that it does not fit >>into a single IP packet this may result in fragmentation > > That's not right either. If it doesn't fit in a UDP packet, the
true > response will be truncated and the client will retry over TCP. If the > UDP packet exceeds PMTU, the packet will be fragmented in transit but > there's no simple way to know that at the application level. There's a > reason EDNS0 let the client suggest a packet size limit, and people > have been tuning their use of it since 1999. > > The entire discussion of response size seems like a throwback to the > 1990s and I would remove it. These days if your DNS doesn't handle yeah, that might be best. > TCP, you already have worse problems, like DNSSEC doesn't work. > > R's, > John -- In my defence, I have been left unsupervised. _______________________________________________ DNSOP mailing list DNSOP@ietf.org https://www.ietf.org/mailman/listinfo/dnsop
