Re: general question: what names for one host with three nic´s

Kevin Darcy kcd at daimlerchrysler.com
Mon Dec 16 18:52:11 UTC 2002


Heiner Keute wrote:

>Hi!
>
>I hope it=B4s ok if I ask this question here. It=B4s a kind of general
>dns-question... in broken english ;-):
>
>I would like to setup a dns for the following scenario:
>
>
>There are two net=B4s: 172.16.0.0 and 192.168.0.0
>and two server=B4s to access from both net=B4s.=20
>
>The server=B4s are connected
>via a 1 Gbit backbone, every server has a 1 Gbit nic. The backbone-net
>has the number 192.168.1.0.
>
>Every server has also two nic=B4s, for each net one.
>
>I call the first server "fileserver" and the second "mailserver". The
>domain is "heiner.local".
>
>Because each nic has it=B4s own number, there is:
>
>fileserver.heiner.local
>eth0: 172.16.0.1
>eth1: 192.168.0.1
>eth2: 192.168.1.1
>
>mailserver.heiner.local
>eth0: 172.16.0.2
>eth1: 192.168.0.2
>eth2: 192.168.1.2
>
>
>What I try to ask is:
>
>How to setup a dns for this, I mean ther is one server with three nic=B4=
s,
>the server has to have three names, one for each number, there has to be
>a zone file for each net - with different names of course for each serve=
r
>- or not?
>
>If there are two users and they want to reach the fileserver one has to
>"speak" to fileserver.heiner.local and the other to
>fileserveroneth1.heiner.local???? Or is there another solution?? Or is
>there a problem between my ears ;-) ?
>
Here at Chrysler, we give each interface a separate DNS name. E.g. on a=20
Sun box, we might call the first ethernet interface=20
foo-hme0.example.chrysler.com, the second interface=20
foo-hme1.example.chrysler.com, the first ATM interface=20
foo-ba0.example.chrysler.com and so forth. Then there is an alias for=20
the "generic" name of the box that most users will use, e.g.=20
foo.example.chrysler.com might be an alias for=20
foo-hme0.example.chrysler.com. If the hme0 interface fails, we can=20
repoint this alias to hme1 somewhat transparently to the user community.

The reason we do things this way is because each interface usually has a=20
specialized function, e.g. we only use the ATM interface for backing up=20
the box to a tape silo. In your environment, it would appear that each=20
interface is available for general use. In that case, I'd probably make=20
the names, e.g. fileserver.heiner.local resolve to all 3 addresses. If=20
you control all of the nameservers that clients will be using to access=20
those boxes, then perhaps you can put "sortlist" definitions in all of=20
them (if they all run sufficiently-modern versions of BIND, or some=20
other DNS software that has an equivalent feature to "sortlist"), so=20
that clients will always try to connect first to the interface which is=20
"closest" to them.

                                                                       =20
                                                    - Kevin





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