nanog mailing list archives
Re: Underscores in host names
From: "Jay R. Ashworth" <jra () baylink com>
Date: Thu, 19 May 2005 12:02:35 -0400
On Thu, May 19, 2005 at 12:01:54PM -0300, MARLON BORBA wrote:
Hmm, they've always teached to me that . (dot) at the end of hostnames indicates the (hidden) Root domain: blah.domain.com.[Root]
This much is true.
And my teachers always said that we don't need to write the final . because every domain belongs to the Root domain.
This, not so much. Well, kinda. Specifically, as I think was noted earlier on the thread in passing, as well, that trailing dot is a hint *to your local name resolver* that says "do not attempt to apply any locally defined DNS search path to this name; look it up once, anchored to the DNS root[0], and if you get an NXDOMAIN, believe it". Semantically, that trailing dot, as it is presented to an application, *is not part of the domain name*. It's ephemeral; only existing on the machine where you type it in -- specifically, it does not get sent in queries (SFIAK), even if you typed it in. So, no, you *don't* need to write it, unless you as an application user are trying specifically to pin the name on the root... but it's invisible to the rest of the system, just as the names themselves are invisible to the TCP stack once you've looked them up and opened a stream. Cheers, -- jra -- Jay R. Ashworth jra () baylink com Designer Baylink RFC 2100 Ashworth & Associates The Things I Think '87 e24 St Petersburg FL USA http://baylink.pitas.com +1 727 647 1274 If you can read this... thank a system administrator. Or two. --me
Current thread:
- Re: Underscores in host names, (continued)
- Re: Underscores in host names bmanning (May 18)
- Re: Underscores in host names Eric A. Hall (May 18)
- Re: Underscores in host names Brad Knowles (May 18)
- Re: Underscores in host names Michael . Dillon (May 19)
- Re: Underscores in host names Paul Vixie (May 18)
- Re: Underscores in host names Eric A. Hall (May 18)
- Re: Underscores in host names Valdis . Kletnieks (May 19)
- Re: Underscores in host names Edward Lewis (May 19)
- Message not available
- Re: Underscores in host names Jay R. Ashworth (May 19)
- Re: Underscores in host names Valdis . Kletnieks (May 19)
- Re: Underscores in host names Roger Marquis (May 19)
- Message not available
- Re: Underscores in host names Jay R. Ashworth (May 19)
- Re: Underscores in host names Edward Lewis (May 19)
- Re: Underscores in host names Eric Brunner-Williams in Portland Maine (May 19)
- Re: Underscores in host names Michael . Dillon (May 20)
- Re: Underscores in host names alex (May 20)
- Re: Underscores in host names william(at)elan.net (May 20)