Introduction to DHCP
DHCP stands for Dynamic Host Configuration Protocol. DHCP is an application layer protocol. It is used to control the network configuration of a host through a remote server. It comes installed as a default feature in most of the contemporary operating systems. DHCP is an excellent alternative to the time-consuming manual configuration of network settings on a host or a network device.
DHCP works on a client-server model. It uses UDP i.e. User Datagram Protocol. It uses:
- UDP port number 67 – DESTIANTION SERVER
- UDP port number 68 – CLIENT
Being a protocol, it has its own set of messages that are exchanged between client and server. In DHCP, 4 main messages are exchanged between the client and the server namely:
That is the reason, it is also called DORA process.
1. DHCP Discover Message:
This is the first message generated by the DHCP Client/host to discover if there is any DHCP server/servers present in a network or not. Discover message is broadcasted to all devices present in the network to find out the presence of DHCP server/servers.
2. DHCP Offer Message:
The Server hears the DHCPDISCOVER request and responds
3. DHCP Request Message:
After receiving DHCP Offer message, the client responds by broadcasting a DHCPREQUEST
4. DHCP ACK Message:
After receiving DHCPREQUEST message, the server may respond in different ways-
Advantages Of DHCP :
- It simplifies the process of IP Address Management.
- It is reliable as the automation helps in minimizing the errors that may arise due to manual IP address configuration.
- It supports large networks as the DHCP server uses multithreading, that can process many client requests simultaneously.
- Set up is less time consuming as the manual configuration is not required.
- It offers a Centralized network client configuration as the configuration information is stored in one place, in the DHCP data store.
Disadvantages of DHCP :
- The client is unable to access the network in the absence of a DHCP Server.
- Major drawback is in terms of security as there is no secure mechanism of authentication for the client.
- DHCP Server can be a single point of failure.
- DHCP client implementations may not work properly with Windows Server 2003’s DHCP server.
Related- DHCP vs RARP
Related- DHCP Snooping