alternative address for same host ?

[Thorsten Jalas]

Hello !

We have an environment in which the same host has to be
addressed with two different addresses - depending on
where the people connect their notebook to the network.
The hosts (server) are situated in site A and have
addresses form 172.x.x.x

If a client connects in site A to the network, they should
use e.x. a dns server to resolve the hosts names to
172.x.x.x addresses.

Site A and B are connected via VPN and all the hosts in A
are masked through static NAT. Every host which has a
172.x.x.x address in A ist visible as 10.x.x.x in B

If a client connects in site B to the network, he should
resolve the same hosts as 10.x.x.x - e.x. using dns or a
host-file.

Does anyone have an idea ?
Is there e.x. a mechanism which lets the client try a
second name resolution if the first ip-address (which he
got from the first name resolution) does not answer ?

Thank´s for yout help.

regards
Thorsten Jalas

 

[Herb Martin]

If the addresses are distinguished by Subnet then you may
find it is already working as you wish.

Win2000+ machines typically do "subnet prioritization" to
pick the best subnet match.

Win2000+ DNS servers do something similar if you check
the box in Server\Properties\Advanced\ for "netmask ordering".

To make these work (efficiently) it must be clear to from the
client address which of the multiple addresses is "better."

Bad example:
Clients on: 192.168.x.y
Server on: 172.16.1.1 and 172.16.250.1
There's no way the client or server can distinguish a preference.

Good example:
Clients on: 192.168.1.y
Server on: 172.16.1.1 and 192.168.1.1
It's obvious that the 192.168.1.1 address is better.

Unclear example:
Clients on: 172.16..1.66/26
Server on: 172.16.1.1 and 172.16.1.65
This one is dependent on the actual subnet mask (and the algorithm)
which I haven't checked.

Bottom line: If you can control the address ranges and they are
"relatively local" to the server addresses then you can make it work.