dig ignores +notcp when doing IXFR (DiG 9.5.0-P2)

[Matthew Pounsett]

I'm trying to debug an IXFR problem with a client, and using dig in its place to compare IXFR requests between it and the misbehaving client.  I noticed that when I do an IXFR with dig it defaults to TCP rather than UDP.  I tried forcing it over with +notcp but I still get a TCP query.

From the man page:
       +[no]tcp
           Use [do not use] TCP when querying name servers. The default
           behavior is to use UDP unless an AXFR or IXFR query is requested,
           in which case a TCP connection is used.

This implies to me that it is simply the default to use TCP for *XFR, but one should be able to override it.  Is that the correct interpretation of the man page?

Even if that is not the correct interpretation, it seems to me that since IXFRs can and do happen over UDP, it should be possible to tell dig to do that.

Is this a bug, or a design flaw?

- Matt