DHCP (Dynamic Host Configuration Protocol)

DHCP (Dynamic Host Configuration Protocol) provides an alternative to manually assigning IP addresses to computers. DHCP automatically assigns, or leases, IP addresses to hosts from a centrally managed pool.

DHCP is an extension of the BootP protocol defined in RFC 951 and is itself described in RFCs 1531, 1533, 1534, 1541, and 1542. Windows 2000 fully supports this standard. Any Windows 2000 computer can act as a DHCP client, and Windows 2000 Server can be configured to act as a DHCP server.

DHCP provides obvious advantages over manual address assignment: there is less administrative hassle, and new machines can be added to the network without dedicated IP addresses. In situations where all machines on the network are not used at once, DHCP allows a small pool of addresses to serve a larger number of machines.

DHCP is simple to install and practical for use in all but the smallest networks. Its disadvantages include the necessity of managing the address pool, the potential for conflicts between DHCP-assigned and manually assigned addresses, and the lack of a consistent address needed for some client applications.

How DHCP Works

DHCP clients and servers communicate with various messages, defined by RFC 1531. Communication is via UDP and uses ports 67 and 68. When a DHCP client initializes, the following process occurs:

  1. The client broadcasts a DHCPDISCOVER message, requesting an IP address lease from any DHCP server. This message includes the ...

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