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From: oberman@amazon.llnl.gov
Newsgroups: comp.protocols.tcp-ip
Subject: Re: UnderscoresDIR/NEW
Message-ID: <1991Mar2.161651.1@amazon.llnl.gov>
Date: 2 Mar 91 23:16:51 GMT
References: <9103022255.AA04928@ucbvax.Berkeley.EDU>
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In article <9103022255.AA04928@ucbvax.Berkeley.EDU>, dmbarton@ralvmm.vnet.ibm.com ("Daniel M. Barton") writes:
> RFC 821 and 822 weren't very clear on what characters a hostname could
> contain.  RFC 952, "DOD Internet Host Table Specification" clarifies
> what characters are legal.  The legal characters are letters, numbers,
> and the hyphen, and the hostname must begin with a letter, and end with
> a letter or digit.  The exact syntax is:

This is out of date information RFC 1122 removes the prohibition of numeric
first characters in host names. Other than that, I know of no changes fron 952.
As far as I can tell, underscores remain a no-no.

That stated, they are quite common and most implementation will allow them. The
only problem is when you hit a system that doesn't. So, please follow the rules
and don't use them. I would also recommend against numeric first characters as
many implementation have not been changed since 1122/1123 were issued.

					R. Kevin Oberman
					Lawrence Livermore National Laboratory
					Internet: oberman@icdc.llnl.gov
   					(415) 422-6955

Disclaimer: Don't take this too seriously. I just like to improve my typing
and probably don't really know anything useful about anything.