On Mon, May 04, 2020 at 09:01:47AM -0700, Fred Baker wrote:
Sending again using the right email address.
On May 4, 2020, at 9:01 AM, Fred Baker <fredbakersba@gmail.com> wrote:
Stepping aside a bit from the question of the FAQ... Yes, this is a change of subject, which is why I changed the subject line.
Does this become a requirement for resolvers using the RSS? RFCs 1034/1035 only hint at it (they define the bit without defining its use case). If, however, I look at RFC 2181, it says
Where TC is set, the partial RRSet that would not completely fit may be left in the response. When a DNS client receives a reply with TC set, it should ignore that response, and query again, using a mechanism, such as a TCP connection, that will permit larger replies.
There was some previous treatment in RFC 1123 (section 6.1.3.2):
DNS resolvers and recursive servers MUST support UDP, and SHOULD support TCP, for sending (non-zone-transfer) queries. Specifically, a DNS resolver or server that is sending a non-zone-transfer query MUST send a UDP query first. If the Answer section of the response is truncated and if the requester supports TCP, it SHOULD try the query again using TCP.
DNS servers MUST be able to service UDP queries and SHOULD be able to service TCP queries. A name server MAY limit the resources it devotes to TCP queries, but it SHOULD NOT refuse to service a TCP query just because it would have succeeded with UDP.
Truncated responses MUST NOT be saved (cached) and later used in such a way that the fact that they are truncated is lost.
As Ray has said, RFC 7766 made TCP a requirement. Mukund