Best way to force a TC=1 response?

Fred Morris m3047 at
Tue May 26 20:50:25 UTC 2020

What's the best way to force an A query via UDP to return a TC=1 result:
a really long CNAME chain?

I want to set up a name that can be used in e.g. ping to perform an end
to end resolution check in application context.

The longer version is that there was a thread on postfix-users not too
long ago about the fact that MUSL libc doesn't do TCP (among other
things) and I want a way to test some hardware and statically built
apps. No jumbo frames here.

I was also mildly surprised to discover that glibc doesn't try TCP if
UDP fails to answer; for some reason I thought it did! Instead it
reports "Temporary failure in name resolution" in the ping example.


Fred Morris

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