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domains. The following formula can be used to calculate the number of trusts in a multiple
master domain model:
M
Ч (M 1) + (R Ч M)
where M is the number of master domains and R is the number of resource domains.
Figure 8-12 has two master domains and three resource domains, so
2
Ч (2 1 ) + (3 Ч 2) = 8
NOTE
The number of trusts can be a factor in determining an appropriate domain structure because
structures with the fewest number of trusts are the easiest to manage.
DHCP
To solve the problems of manual addressing, the Internet Engineering Task Force (IETF)
developed DHCP, the Dynamic Host Configuration Protocol. DHCP is designed to
automatically provide clients with a valid IP address and related configuration information.
Each range of addresses that a DHCP server manages is called a scope.
DHCP Scopes
Configure a range of addresses for every IP subnet where clients will request a DHCP address.
Configure a DHCP server to serve several scopes because the DHCP server or servers do not
need to be physically connected to the same network as the client. If the DHCP server is on a
different IP subnet from the client, configure the DHCP relay to forward DHCP requests to your
DHCP server.
DHCP Relay
DHCP relay typically runs on a router. Relay support is available on Windows NT Server
version 4.0 and Windows 2000 Server. On Cisco 700 series routers, turn on DHCP relay with
the set dhcp relay command.
DHCP centralizes, manages, and assigns IP addresses to network clients dynamically. Each
time a DHCP client starts, it requests an IP address, a subnet mask, and a default gateway. Here
are some of the advantages of using DHCP:
·
Lower administrative overhead
·
Mistakes made from incorrect configuration lessened
·
Saves time
87200333.book Page 277 Wednesday, August 22, 2001 2:37 PM