Question: Explain DHCP in detail.

Question: Question: Explain DHCP in detail. 

Answer 

The DHCP protocol gives the network administrator a method to configure the network from a
centralised area. With the help of DHCP, easy handling of new users and reuse of IP addresses
can be achieved.

DHCP is a network protocol that is used to assign various network parameters to a device.
This greatly simplifies administration of a network, since there is no need to assign static
network parameters for each device.

DHCP is a client-server protocol. A client is a device that is configured to use DHCP to
request network parameters from a DHCP server. DHCP server maintains a pool of available
IP addresses and assigned one of them to the host. A DHCP server can also provide some
other parameters, such as:

• subnet mask
• default gateway
• domain name
• DNS server

Cisco routers can be configured as both DHCP client and DHCP server.

DHCP process explained:

DHCP client goes through the four step process:

DHCP port number for server is 67 and for the client is 68. It is a Client server protocol which
uses UDP services

1: A DHCP client sends a broadcast packet (DHCP Discover) to discover DHCP servers on the
LAN segment.

2: The DHCP servers receive the DHCP Discover packet and respond with DHCP Offer packets,
offering IP addressing information.

3: If the client receives the DHCP Offer packets from multiple DHCP servers, the first DHCP
Offer packet is accepted. The client responds by broadcasting a DHCP Request packet,
requesting the network parameters from the server that responded first.

4: The DHCP server approves the lease with a DHCP Acknowledgement packet. The packet
includes the lease duration and other configuration information.

Advantages – The advantages of using DHCP include:

• centralized management of IP addresses
• ease of adding new clients to a network
• reuse of IP addresses reducing the total number of IP addresses that are required
• simple reconfiguration of the IP address space on the DHCP server without needing to

  reconfigure each client

Disadvantages – Disadvantage of using DHCP is:

• IP conflict can occur