Sunday, May 25, 2008

What is DHCP server?

Dynamic Host Configurations Protocol, also known as DHCP,  is a network protocol that enables the DHCP server to assign an IP address to the networked devices or clients to obtain neccessary parameters in order to establish Internet Procotol (IP) network.

How does DHCP works ?


  1. The client device turned on with DHCP client.
  2. This client will broadcast a number of requests ( DISCOVER and DHCPDISCOVER ) packets in the network to look for reply from DHCP server.
  3. The router ( if the router itself is not a DHCP server ) will route the DISCOVER packet to DHCP server.
  4. Once the DHCP server received the DISCOVER packet, it will looks into the pre-configured policies and availability then determines the appropriate IP settings to assign to the client station.
  5. The DHCP server will send an OFFER or DHCPOFFER packet to the client based on the MAC address with the neccessary parameters ( i.e. IP address, gateway, DNS, WINS etc. )
  6. The client will send REQUEST or DHCPREQUEST packet back to the DHCP server and inform the server that it intend to use the configurations info offered.
  7. The server will then reply with an ACK or DHCPACK packet back to the client and confirmed that the client may use the information for a certain period ( lease time ) as per configured in the policy.

 More information on DHCP at Wikipedia

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