DNS RFC Dependency Graphs
Spurred by a recent Slashdot posting, I’ve produced some graphs showing the relationships between the RFCs which define the DNS protocol.
The graphs (which are in SVG format) split the DNS-related RFCs into three groups (although some RFCs end up in more than one group):
The point of these graphs is not to show which RFCs refer to other RFCs, but to show which RFCs update or obsolete other RFCs. Hence the graphs give an “at a glance” overview of which RFCs define the DNS protocol as it is now.
Boxes in grey indicate obsoleted RFCs, and square boxes indicate Informational or Best Current Practice documents. Hovering over a box should tell you the title of the RFC, and clicking on a box will take you to the RFC itself.
The picture below is just a low resolution sample – click on the picture or on the links above to access the scalable SVG versions.
Please let me know if you believe I’ve missed anything, or miscategorised any document.

(7 votes, average: 4.57 out of 5)
May 24th, 2010 at 2:19 pm
This is _very_ nice. I take it this was produced from traversing the “Obsoletes”/”Updates” notations in rfc-index.txt. It does flag up deficiencies in these notations, though. For example, RFC 5155 section 10.2 updates RFC 2672 section 3; however this escapes mention in rfc-index.txt for some reason. I’m not sure what mechanisms exist for correcting rfc-index.txt.
May 24th, 2010 at 6:26 pm
I noticed a few omissions in the RR defs: RFC2536, RFC2537, RFC2539, RFC3110. I didn’t check exhaustively so there may be more.
May 25th, 2010 at 7:05 am
I do not see the RFC about IDN. Is it because I’ve read too fast or because you do not see them as “protocols”?
May 25th, 2010 at 9:42 am
They’re not there, because I forgot them.
I’ll add a new group once the new IDNAbis specifications are published.
May 25th, 2010 at 9:56 am
@Geoff – actually I’m using the XML version, it’s a lot easier to parse :)
Re: missing updates – if the RFC header doesn’t declare that it updates another RFC then that’s what the index says. You’d have to take that up with the authors of 5155 ;-)
I’ll check the status of those other RFCs. They didn’t hit my list because they’re not mentioned in the IANA table of DNS TYPE codes.
May 25th, 2010 at 4:25 pm
Ray — Yes, we should probably submit that as errata, so it gets included in the next iteration of docs, whenever that happens. Not sure why it wasn’t caught before.
Re: other RFCs: that would explain it. I suspect there are quite a few RR type RFCs that will escape identification via that method.
August 26th, 2010 at 12:27 pm
Now, you can add the following RFCs : 3492, 5890, 5894, 5891, 5892, 5893 and 5966
July 3rd, 2011 at 9:53 pm
Any chance you could give us some hints on how to do this? I would love to do this for mail-related RFCs and would like to avoid reinventing the wheel if possible!
Thanks
Anton
July 28th, 2011 at 5:18 pm
@Anton The source code (including initial config files for SMTP, IMAP, POP and DKIM) is available from http://download.nominet.org.uk/rfcdeps/src/