1 host, 2 IP's

[JR]

Our Mainframe system interfaces with our administrative
network via two 10/100 NICs, IP addresses = 172.16.9.106 &
172.16.9.110.

All mainframe client sessions are configured to point to
the mainframe NIC's with the hostname "s390host" - and in
the DNS record, there are two entries for "s390host"...one
for each IP.

Everyone seems to connect to the *.110 address first. We
would like to have load-balancing of some sort -
where...say...every other client picks up *110 and the
alternate clients pick up *.106.

The client PC's use DHCP to pick up their own addresses.

Is DNS where we should be looking for this functionality,
or should we turn our attention to another service,
entirely?

 

[Kevin D. Goodknecht [MVP]]

In

Our Mainframe system interfaces with our administrative
network via two 10/100 NICs, IP addresses = 172.16.9.106 &
172.16.9.110.

All mainframe client sessions are configured to point to
the mainframe NIC's with the hostname "s390host" - and in
the DNS record, there are two entries for "s390host"...one
for each IP.

Everyone seems to connect to the *.110 address first. We
would like to have load-balancing of some sort -
where...say...every other client picks up *110 and the
alternate clients pick up *.106.

The client PC's use DHCP to pick up their own addresses.

Is DNS where we should be looking for this functionality,
or should we turn our attention to another service,
entirely?

DNS is not very good at load balancing, it just hands the record out with
the closest IP to the subnet it connects from. It is not really recommended
to multihome a DC, or run RAS on the DC.
Are the multihomed IP addresses on the same subnet?
292822 - Name Resolution and Connectivity Issues on Windows 2000 Domain
Controller
with Routing and Remote Access and DNS Installed
http://support.microsoft.com/default.aspx?scid=kb;en-us;292822&FR=1
272294 - Active Directory Communication Fails on Multihomed Domain
Controllers
http://support.microsoft.com/default.aspx?scid=kb;en-us;272294&FR=1

 

[Guest]

Thanks for the reply, Kevin

Most of the important boxes reside on the same subnet. We have a 172.16.0.0 network and this is the 172.16.8.*-172.16.15.* subnet that holds the Mainframe, most of the clients, and the administrative servers. We have an offsite location that also uses the Mainframe...they are in the 172.16.56.* subnet...but I'm assuming that if we fix the problem for one subnet, we'll fix it for all

The *obvious* fix would be to have I.S. enter one IP on half the clients and the second IP on the other half, and remove the DNS name entirely. Static IP's make for such a headache when the NIC address changes, though...

 

[Kevin D. Goodknecht [MVP]]

In

Thanks for the reply, Kevin.

Most of the important boxes reside on the same subnet. We have a
172.16.0.0 network and this is the 172.16.8.*-172.16.15.* subnet that
holds the Mainframe, most of the clients, and the administrative
servers. We have an offsite location that also uses the
Mainframe...they are in the 172.16.56.* subnet...but I'm assuming
that if we fix the problem for one subnet, we'll fix it for all.

The *obvious* fix would be to have I.S. enter one IP on half the
clients and the second IP on the other half, and remove the DNS name
entirely. Static IP's make for such a headache when the NIC address
changes, though....

Not really, the best way is to NOT use two subnets on the DC, just use one
subent on the DC then use a Subnet mask to mak the IP available to both
subnets. In your case the Subnet mask would be 255.255.192.0 that would make
it possible for the DC to cummunicate with both subnets with one IP address.
See this:
CIDR range 172.16.0.0/18
Netmask 255.255.192.0
Wildcard Bits 0.0.63.255
First IP in range 172.16.0.0 (network address)
Last IP in range 172.16.63.255 (broadcast address)
First useable IP in range 172.16.0.1
Last useable IP in range 172.16.63.254
Number of useable IPs in range 16382