Check-names question

[J Doe]

Hello,

On a low volume e-mail server I run, I also run BIND 9.20.13 as a 
recursive resolver.  In the configuration file (named.conf), I have the 
following directive:

check-names response warn;

In my BIND logs I recently noticed the following:

6-Sep-2025 14:59:04.619 resolver: notice: check-names warning 
engadget-ycpi-media_edge.g03.yahoodns.net/A/IN

I was under the impression that check-names would alert me to name 
issues in the zones I host on this server (I host a custom DNSBL zone), 
but this also applies to foreign zones that I do not host ?

Am I correct, as well, that BIND is taking issue with the _ character in 
this particular example ?  I seem to think in the original RFC for DNS 
this wasn't allowed.

Thanks,

- J