Configuring DHCP server
Posted on Tuesday, October 13, 2009
This article was posted in Microsoft
- DHCP server allows system administrator to automatically assign IP addresses, subnet masks and other configuration information like DNS and WINS servers to client computers on local network.
- Through the use of DHCP server network administrators save time required for configuration and re-configuration of computers.
- Administrator should install DHCP service on a computer that was assigned a static IP address (this prevents clients to look all over the subnet to get their addresses renewed)
- You need to have administrative privileges to install and administer DHCP server
- You need to authorize your DHCP server if it is to be integrated in AD network (Person authorizing the DHCP server needs to be a member of the enterprise administrators security group). Stand alone DHCP servers can still be deployed but they should not share subnet with authorized DHCP servers. Stand alone servers that are deployed together with authorized servers are called rogue servers. The rogue server will automatically stop its DHCP service when it detects authorized server on the subnet.
- DHCP scope is a pool of IP addresses within a logical subnet which DHCP server assigns to its clients. Scopes provide for IP address management.
- When an IP is offered for a client it is said that IP address is a lease. When the lease is made it is said to be active. Leases are renewed for different reasons, client will try to renew when 50% of old lease expires.
- The DHCP server has to have IP address compatible with the scope it is assigned, i.e. the server itself has to be in the scope.
- The 80/20 rule – to provide for fault tolerance in an environment with two DHCP servers, the first server (A) should have 80% of the addresses for his local subnet, 20% of addresses for the subnet on which another DNS server (B) is present. The same assignment is repeated on server (B) which gets 80% of addresses in its own subnet and 20% of addresses in the subnet on which server (A) is present. This concept is applied when 2 or more DHCP servers are present.
- Reservations are placements in the scope reserved for specific computers. You reserve IP address for a specific network adapter using its MAC address. To create new reservation open the scope in which you want to create new reservation r-click Reservations and select New Reservation. Reservations cannot be used interchangeably with manual static configurations. Reservations don’t work when address is simultaneously reserved and excluded. Reservations are used as an alternative to static addresses for computers that are no essential to network function (i.e. not critical servers).
- The scope needs to be activated before the server can hand out addresses (for AD integration it also need to be authorized). To activate a scope open the DHCP console, select scope you want to activate, from actions menu select Activate.
- Exclusion range – group of IP addresses residing in the scope that administrator doesn’t wish to be leased to DHCP clients
- DHCP is na extension of the Boot Protocol (BOOTP). Microsoft DHCP server can assign addresses to BOOTP clients.