Date: Thu, 11 Sep 1997 17:28:53 -0700 (PDT) From: "Jonathan M. Bresler" <jmb> To: brandon@roguetrader.com (Brandon Gillespie) Cc: greg@smokey.prismnet.com, freebsd-isp@FreeBSD.ORG, freebsd-questions@FreeBSD.ORG Subject: Re: BIND Question Message-ID: <199709120028.RAA11810@hub.freebsd.org> In-Reply-To: <Pine.BSF.3.96.970911145341.13683A-100000@roguetrader.com> from "Brandon Gillespie" at Sep 11, 97 02:56:46 pm
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Brandon Gillespie wrote: > > On Thu, 11 Sep 1997, Greg Stringfellow wrote: > > > Here is an interesting question, or at least to me right now. > > > > I've got a customer who is trying to send mail to a particular location. The > > hostname is "HPISD_ADMIN.HIGHLANDPARK.K12.TX.US". I remember reading > > somewhere about the underscores in a hostname not being valid. But I just > > can't seem to track it down. > > You are right, underscores are not a valid part of a domain name, even > though old DNS servers would allow them (all that is valid is a-z0-9 and a > dash, I believe). rfc1123 amends rfc952 rfc1123: 2.1 Host Names and Numbers The syntax of a legal Internet host name was specified in RFC-952 [DNS:4]. One aspect of host name syntax is hereby changed: the restriction on the first character is relaxed to allow either a letter or a digit. Host software MUST support this more liberal syntax. rfc952. "DOD INTERNET HOST TABLE SPECIFICATION" oct '85 not listed in std-index.txt but referenced by rfc1123 which is listed in std-index.txt rfc952: 1. A "name" (Net, Host, Gateway, or Domain name) is a text string up to 24 characters drawn from the alphabet (A-Z), digits (0-9), minus sign (-), and period (.). Note that periods are only allowed when they serve to delimit components of "domain style names". (See RFC-921, "Domain Name System Implementation Schedule", for background). No blank or space characters are permitted as part of a name. No distinction is made between upper and lower case. The first character must be an alpha character. The last character must not be a minus sign or period. A host which serves as a GATEWAY should have "-GATEWAY" or "-GW" as part of its name. Hosts which do not serve as Internet gateways should not use "-GATEWAY" and "-GW" as part of their names. A host which is a TAC should have "-TAC" as the last part of its host name, if it is a DoD host. Single character names or nicknames are not allowed. jmb
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