What is DHCP?

Definition

DHCP stands for Dynamic Host Configuration Protocol. It is a protocol used when a computer is connecting on a local network to dynamically and automatically get its IP configuration, without having to specify it "by hand". The main goal is to simplify the administration of a local network.

Usually, we consider DHCP as a protocol used to distribute IP addresses, but was also designed at the beginning as a complement to BOOTP (Bootstrap Protocol), which is used for instance when we want to start a diskless machine: DHCP will help it find a first program to boot with; the program is then downloaded by the diskless machine through the local network. In the same way, we can completely install a machine from scratch through the local network. This latter option is very interesting to maintain a huge amount of machines.

Current versions of DHCP servers work for IPv4 (IP addresses are coded with 4 bytes). The IETF is studying a new version for IPv6 (IP addresses coded with 16 bytes).

References

RFCs:

• RFC951: BOOTP
• RFC1497: vendor extensions options
• RFC1541: DHCP
• RFC1542: interaction between BOOTP and DHCP
• RFC2131: complement to RFC1541
• RFC2132: complement to options vendor extensions options

Specifications and Java API: dhcp.org
The ISC Web site: http://www.isc.org
Microsoft Web site: BOOTP, DHCP, DNS servers

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