Re: check-names settings - DNS

This is a discussion on Re: check-names settings - DNS ; Labels start with a letter or digit. Labels end with a letter or digit. Letter, digit or hypen in the middle of the label. All labels meet the above with the exception of a mbox where second to last labels ...

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Thread: Re: check-names settings

  1. Re: check-names settings


    Labels start with a letter or digit. Labels end with a
    letter or digit. Letter, digit or hypen in the middle of
    the label.

    All labels meet the above with the exception of a mbox where
    second to last labels meet the above.

    A single period can also be used as a place marker.

    The rules are applied to the owner names of A, AAAA and
    MX records.
    NS and MX records rdata.
    IN-ADDR.ARPA and IP6.ARPA PTR records rdata.
    (I don't think I've missed any cases).

    Underscore was choosen for SRV records so that they would
    *not* clash with hostnames.

    Active directory similarly uses underscore to *not* clash
    with host names, gc uses a A record but as *all* the
    particiants in AD are *known* to cope it is not a problem.

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


  2. Re: check-names settings

    In article ,
    Mark Andrews wrote:

    > Labels start with a letter or digit. Labels end with a
    > letter or digit. Letter, digit or hypen in the middle of
    > the label.
    >
    > All labels meet the above with the exception of a mbox where
    > second to last labels meet the above.
    >
    > A single period can also be used as a place marker.
    >
    > The rules are applied to the owner names of A, AAAA and
    > MX records.
    > NS and MX records rdata.
    > IN-ADDR.ARPA and IP6.ARPA PTR records rdata.
    > (I don't think I've missed any cases).
    >
    > Underscore was choosen for SRV records so that they would
    > *not* clash with hostnames.


    Even folks who put underscores in hostnames are practically never going
    to clash with SRV records. Labels in SRV records *start* with
    underscores, and no one does that with hostnames, even if their
    nameservers allow it. Underscores, like hyphens in standard-conforming
    hostnames, are always used as word separators in hostnames.

    --
    Barry Margolin, barmar@alum.mit.edu
    Arlington, MA
    *** PLEASE don't copy me on replies, I'll read them in the group ***


  3. Re: check-names settings

    "Mark Andrews" wrote in message
    news:gaeumj$gfv$1@sf1.isc.org...
    > Labels start with a letter or digit. Labels end with a
    > letter or digit. Letter, digit or hypen in the middle of
    > the label.


    Labels FOR HOSTNAMES meet the above. Not all labels map to hosts.




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