[dns-operations] underscores in domain names

[Jim Reid]

> On 12 Sep 2017, at 10:19, James Stevens <James.Stevens at jrcs.co.uk> wrote:
> 
> It would be impossible to disagree - just interesting to see that
> underscore in public names is astonishingly common - like SRV records,
> so I assumed underscore was reasonably well supported.

It is perfectly legal to use underscores in domain names. They can't be used in hostnames.

In fact when SRV records were invented, the convention of _proto and _service was deliberately chosen so those names could not clash with hostnames. See RFC2782.