SUMMARY: alternate DNS zone setup

Date: Thu Jun 19 1997 - 06:37:41 CDT

My original query was as follows :-
     I have a situation where we want to alias our DNS zone e.g allow our
     zone name to be referenced by another name e.g.
     I have done this before using and as I recollect we need to do two
     1) change our /etc/named.boot file to include the alternate zone name,
        something like :-
     directory /var/named
     cache .
     primary zone-A.hosts
     primary zone-B.hosts
     primary primary named.local
     2) Set up the zone files for the alternate zone (e.g. derwent-B) set
     up to point back at the main zone name (i.e. derwent) with CNAME's as
     @ IN SOA (
     199618040 ; Serial
     10800 ; Refresh every 3 hours
     3600 ; Retry every hour
     604800 ; Expire after a week
     86400 ) ; Minimum ttl of 1 day
     NS MX 5 hosta
          CNAME hostb CNAME hostc CNAME www
I got two different replies as follows :-
1) From Jochen Bern <bern@TI.Uni-Trier.DE>
     Especially when the Objective is to have the Domain Name *switched
     over* to the other in the long Run, I'ld suggest to avoid CNAMEs
     (sendmail, Web Robots etc. might decide to replace CNAMEs with primary
     which leaves you glued to Square one). Try the following:
     1) Introduce the second Domain to your named.
     2) As Source File for the direct Map, use THE VERY SAME Data as for
     old direct Map. (If you use plain Files, convert one into the other
     with sed -e 's/old\.dom\.ain/new\.dom\.ain/g' ; If you have some other
     Mechanism create this File, e.g., from /etc/hosts, duplicate the
     Mechanism with appropriate Changes.)
     This might require minor Changes (you can't do "$ORIGIN -
     host.derwent IN A ..." anymore), but they improve your Setup's Sanity,
     so they're not really for naught ...
     3) Depending on what your Mechanism to automatically produce the
     Map is (you SHOULD determine the indirect Map from the direct Map
     automatically!), you'll either want to find the Place where you get to
     select the direct Map they're derived from, or have it run on
     both Domainnames and select the appropriate Output File in named.boot.
     4) Announce the new Domain to the NIC.
     5) Once the new Domain "is stable" (takes nothing but having the NIC
     have it referring to your Nameserver and debugging the Changes in 2)
     and 3)), you can reiterate Step 3) and have the PTRs point to the new
     Domainname instead of the old.
     6) When finally the Changeover has settled and you want to remove the
     old Domain from the direct Maps, too, just unregister it from the NIC
     and undo Step 2) so that only direct Maps for the new Domain get
     However, if you intend to use both Names instead of just changing
     over, CNAMEs are definitely the Way to go (as they don't introduce
     Hostnames with improper indirect Mapping).
2) From (Reto Lichtensteiger)
     The suggestion here was to just point the altenate zone at the
     existing primary zone as follows :-
     primary zone-A.hosts
     primary zone-A.hosts
     primary primary named.local
     If your zone file is in the format:
     hostname IN A
     Then bind will append the contents of the $ORIGIN macro (ie, whatever
     you have in the second field of the primary statement in named.boot)
     to the hostname. Thus the same zone file can be used for
     This trick will only work, of course, if you want all the systems to
     be identical. You can use FQDN names for hosts that exist only in one
     domain or t'other, but named will complain ...
     <> 3) Contact the Intern-nic (?) with regarding our dual zone
     I don't think they'd care about "dual zone authority"; simply tell
     whoever runs that your server is primary for
To summarise I havn't actually implemented the zone yet but as we intend to
run two identical zones rather than changing our zone name I will be using
the try the latter of the two suggestions.

Many Thanks to the respondees

* *
* Stuart Burch Derwent Information Publishing *
* (System Administrator/Developer) 14 Great Queens Street *
* London *
* Group Business Development WC2B 5DF. *
* *
* Email: Tel: 0171-344 2800 x 3001 *
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