underscores in A queries

[Lee]

On 4/9/21, John W. Blue via bind-users  wrote:
> It would seem that underscores is one of those characters in DNS that leads
> a double life.
>
> RFC’s say that underscores are disallowed for use in hostnames

Right.  But it's **hostnames** and not everyone enforces that rule :(

> but SRV
> records use it to indicate service type et al.

SRV records aren't hostnames, nor are CNAME records, TXT, etc.

I've got this bit in my notes re "check-names response fail;"
    # also see  dns-operations at lists.dns-oarc.net
    #          [dns-operations] about the underline in hostname
    # where the consensus is to not do this check on resolvers

Regards,
Lee