RESOLUTION
To resolve each possible cause, use one of these solutions:
Solution for Scenario 1
A DHCP server can only service requests for a scope whose network ID is the
same as the network ID of its IP address.
Make sure that the server's IP address falls in the same IP network ID as
the scope it is servicing. For example, a server with IP address in the
192.168.0.0 network cannot assign addresses from a scope like 10.0.0.0,
unless superscoping is used.
For additional information, please see the following articles in the
Microsoft Knowledge Base:
139904
How to Configure Your DHCP Server Scope
169140
Using DHCP to Assign IP Addresses to Secondary Networks
161571
Using DHCP "Superscopes" to Serve Multiple Logical Subnets
Solution for Scenario 2
A DHCP server can provide IP addresses to client computers spanning
multiple subnets if the router that separates them can act as an RFC 1542
(BOOTP) relay agent.
- Configure a BOOTP/DHCP Relay Agent on the client segment. This can be
the router itself or a Windows NT computer running the DHCP relay
service.
- Configure a DHCP scope to match the network address on the other side of
the router where the clients are. Make sure the subnet mask is correct.
- Do not configure a default gateway on the DHCP server's NIC such that
it is the same address as that of the router supporting the subnet
where the clients are.
- Do not include that subnet's scope in any superscope that is
configured on the DHCP server's LAN segment.
- Make sure there is only one logical route between the server and the
remote clients.
For additional information, please see the following article in the
Microsoft Knowledge Base:
174765
How to Configure Microsoft DHCP Server for BOOTP Clients
Solution for Scenario 3
Make sure that you do not configure multiple DHCP servers on the same LAN
with overlapping scopes.
In case of Small Business Server, the DHCP service will automatically stop
when it detects another DHCP server on the LAN.