4 part domain names

[Peter Risdon]

Hexren wrote:
> JM> On Wed, Nov 24, 2004 at 04:08:06PM +0100, Hexren wrote:
> JM> : location. 510 could identify a rack or a datacenter so that
> JM> : us.510.mail.example.com means "a mail server in the datecenter with
> JM> : the id 510 which serves the United States".
> 
> JM> So 'us.510.mail' is an atomic, arbitrary identifier.  All three as a unit
> JM> identify a certain node, and are selected purely for convenience of human
> JM> operators, right?
> 
> I would say yes.
> 
> 
> JM> I'm just making sure that the network doesn't treat 'us.510.mail' any
> JM> different than it would treat 'foobar', right?
> 
> I would say yes too.


How does this square with the fact, as I understand it, that I can 
delegate authority for mail.example.com to new nameservers which can 
then publish host information about this zone? Here's the example zone 
file extracts from the article I linked to in an earlier mail, which is 
delegating authority for the sub domain us.example.com:

<quote>
; zone fragment for 'zone name' example.com
; name servers in the same zone
example.com.  IN      SOA   ns1.example.com. root.example.com. (
                2003080800 ; serial number
                2h         ; refresh =  2 hours
                15M        ; update retry = 15 minutes
                3W12h      ; expiry = 3 weeks + 12 hours
                2h20M      ; minimum = 2 hours + 20 minutes
                )
; main domain name servers
               IN      NS     ns1.example.com.
               IN      NS     ns2.example.com.
; mail domain mail servers
               IN      MX      mail.example.com.
; A records for name servers above
ns1           IN      A      192.168.0.3
ns2           IN      A      192.168.0.4
; A record for mail server above
mail          IN      A      192.168.0.5
....

; sub-domain definitions
$ORIGIN us.example.com.
; we define two name servers for the sub-domain
@             IN      NS     ns3.us.example.com.
; the record above could have been written without the $ORIGIN as
; us.example.com. IN NS ns1.us.example.com.
ns3           IN      A      10.10.0.24 ; 'glue' record
; the record above could have been written as
; ns3.us.example.com. A 10.10.0.24 if it's less confusing
</quote>

Peter.

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