Reverse DNS RFCs and Recommendations

Wed Oct 30 22:21:38 UTC 2013

In message <CACnPsNUxTa3vYQSxuTE4x9NXFm_o+2Bp7HqMBApXcm5_G5Zr2Q at mail.gmail.com>
, Scott Howard writes:
> On Wed, Oct 30, 2013 at 2:33 PM, Nolan Rollo <nrollo at kw-corp.com> wrote:
> 
> > So in the four examples below, 3 of them preface the IP with an alpha
> > character. Charter however, starts the rDNS off with a number. I'm not
> > arguing with anyone but what potential problems could that cause with DNS?
> > I'm also thinking of the famous  www.1and1.com, where the number "1"
> > starts off one of the sections.
> >
> 
> Using domain name parts that start with a number will likely cause issues
> for anyone running resolvers written in the 80's.
> 
> Anyone running resolvers that are less than ~25 years will likely not have
> any issues.
> 
>   Scott

To be more precise it will cause no problems with the DNS.  Some
pre RFC 1123 gethostbyname implementations may reject the name
but the DNS doesn't care.

Mark
-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: marka at isc.org