Errors-to: owner-drums@CS.UTK.EDU
Message-Id: <199505301556.LAA06778@wilma.cs.utk.edu>
From: Keith Moore <moore@CS.UTK.EDU>
To: Eric Thomas <ERIC@SEARN.SUNET.SE>
cc: drums@CS.UTK.EDU, moore@CS.UTK.EDU
Subject: Re: getting started 
In-reply-to: Your message of "Tue, 30 May 1995 13:48:57 +0200."
             <199505301214.IAA22394@CS.UTK.EDU> 
Date: Tue, 30 May 1995 11:56:20 -0400
Sender: moore@CS.UTK.EDU


> One feature that I think needs to be clarified in both 821 and 822
> (et seq) is whether underscore and leading numbers are accepted in
> hostnames.
>
> Right now we have a nice mess where 822 allows underscores, 821
> doesn't, and neither does the DNS, but then bind does and so does
> sendmail, so major vendors (like IBM) have been rioted into
> modifying their SMTP software to allow it.  Due to the lack of a
> clear statement about the underscore, it is harder for vendors to
> defend their position.
>
> For leading numeric characters we have another mess where the
> (modified) DNS standards allow it, but 821 doesn't. So in principle
> they should be rejected, but then we all know they're used. I think
> the intent of 1123 was to modify 821 to allow it, but this hasn't
> been stated explicitly enough.

Agreed.  <draft-ietf-mailext-smtpas-01.txt> attempted to resolve this
issue like so:

] 2.12.  Domains
] 
] RFC 821 and RFC 822 were developed before the domain name system
] had fully stabilized.   The domain syntax for both (using
] RFC 822's syntax) is:
]        domain-ref = sub-domain *("." sub-domain)
] 
]        sub-domain = let-dig *(ldh-str)
]        domain-literal = "[" IP-address-literal "]"
]        IP-address-literal = snum 3*("." snum)
]        snum = one, two, or three digits representing a decimal
]            integer value in the range 0 through 255
]        let-dig = Alpha / Digit
]        ldh-str = *( Alpha / Digit / "-" ) 1*(let-dig)
] 
]        Alpha = ASCII character in the range A-Z or a-z.  As specified in
]            RFC1035, case is not significant in domain strings.
]        Digit = 0 - 9
] 
]        The # syntax for domain literals is believed to not be in
]        active use.   Its occasional appearances cause confusion
]        and is now deprecated.  Hence, SMTP clients SHOULD NOT
]        use it, and SHOULD use the bracketed dotted octet syntax
]        when it is necessary to explicitly use IP addresses.
] 
]        Characters outside the set of specials, alphas, digits,
]        and hyphen MUST NOT appear in domain names.  In
]        particular, the underscore character is not permitted.
] 
] 
]        Note that the IP-address-literal syntax above specifies four
]        or more of these numbers to accomodate IPv6.

> If you put all the stuff in one document life will be much simpler
> for everyone.

That's the idea.  Of course, after we do so there will soon be other
amendments.  But at least we'll catch up.

As for being able to know what the latest set of revisions is, the STD
series of documents was supposed to alleviate that problem.  Of
course, nobody ever refers to standards by their STD numbers even if
they exist.  A related problem is that STD numbers aren't assigned
until something is a Full Internet Standard, even though these
products based on earlier drafts are already widely deployed before
then.  By the time a document is Full Standard, people are already
used to referring to it by its RFC number.

Keith