A server is essentially a computer software/program or computer hardware that is meant to provide functionality (services) to its clients, which are other programs or devices, through an architecture that is referred to as the client-server model. The services that servers deliver include sharing resources or data, carrying out computation etc. A single server is capable of serving more than one client and a single client can use many servers. There are many types of servers, such as file servers, print servers, mail servers, database servers, application servers, game servers, DHCP servers, web servers etc. The focus of this blog is on DHCP servers.
A
DHCP (Dynamic Host Configuration Protocol) server refers to a network server
which automatically assigns IP addresses, network parameters and default
gateways to client devices. It uses a protocol known as the Dynamic Host Configuration
Protocol (DHCP) for the purpose of responding to clients’ broadcast queries.
DHCP is an enhanced version of an older protocol that is known as BOOTP.
Moreover, DHCP forms an essential part of the DDI solution.
The
needed network parameters are automatically sent by a DHCP server, so that
clients can properly communicate over the network. In its absence, every client
joining the network, has to be set up manually by the network administrator.
This can lead to inefficiency, especially in networks that are large. Each
client is assigned a unique and dynamic IP address by a DHCP server. This
unique and dynamic IP address changes when the lease of the client for that
particular IP address expires. This protocol for network management is used for
automating the process related to configuring devices on Internet Protocol
networks. This enables these to use network services, which include, DNS
(Domain Name System), NTP (Network Time Protocol) as well as any communication
protocol that is based on UDP (User Datagram Protocol) or TCP (Transmission
Control Protocol).
DHCP
Usage
The
main usages of DHCP are mentioned below, in no particular order.
- For initial client connection, wherein an IP address along with the other parameter values that are required for accessing network services are requested by the client from the DHCP server
- For the extension of IP usage, wherein the DHCP server is contacted by the client for extending its current IP address’ usage.
- For client connection post reboot, wherein the DHCP server is contacted by the client in order to confirm the use of the same IP address which was being used prior to the reboot.
- For client disconnection, wherein the DHCP server is requested by the client to release its IP address.
DHCP
Server, Configuration Data, Key Values
A
DHCP server sends configuration data in accordance with the policy of the
administrator with regard to a requesting client. The requested common network
parameters, which are referred to as the DHCP options, include domain name server,
subnet mask, router, hostname and domain name. The requesting client doesn’t
have any IP address when it joins the network. Hence, it broadcasts a request
and the protocol gets used in a very early stage with regard to IP
communication. The client will have to use a predefined IP address (static IP
address) when such a dynamic protocol isn’t used for getting an IP address. A
static IP address is configured manually in configuration files on the client
network interface.
The
main key values with regard to DHCP service have to do with, a reduction in
operation tasks, wherein the network administrator doesn’t need to configure
manually each client prior to it using the network; optimization of the IP
addressing plan, wherein the addresses that are no longer in use are provided
to new clients along with proper and easy management of user mobility, wherein
the administrator has no need to configure manually a client due to a change in
network access point.
DHCP
Lease
The
IP address information that is assigned by DHCP is valid for a limited
duration, which is known as the DHCP lease. This validity period is referred to
as the DHCP lease time. As soon as the lease expires, the client is unable to
use the IP address and all communication with the IP network stops, unless the
client requests for extending the rent for the lease through the cycle for DHCP
lease renewal.
DHCP
Options
DHCP
options serve the purpose of providing information automatically to clients
with regard to the network services that can be used. These options function as
efficient ways for pushing the time server’s, the DNS server’s, the mail
server’s and the printer server’s IP addresses. DHCP options also act to
provide a file server and a file name for the use of the client for starting a
specific boot process, which is usually used by Wi-Fi access points, IP phones,
auto-installing clients and the servers with Preboot eXecution Environment
(PXE).
DHCP
Server’s Main Benefits
It
is always better to use a centralized DHCP server, especially for network
environments which require the support of both, DHCP for IPv6 and for IPv4
simultaneously. Both protocols are supported by the majority of DHCP server
vendors. This allows one to use the same management interface for DHCP for IPv6
and for IPv4.
The
major benefits of using a DHCPv6 are as follows-
- A DHCPv6 server, which is integrated into one’s IPv6’s IPAM (IP Address Management) system, enables IPv6-enabled client nodes’ visibility.
- Logging and management interfaces are provided by DHCP servers. This helps administrators in the management of their IP address’ scopes.
- Redundancy and high availability are provided by DHCP servers. When one DHCP server fails, the clients preserve their current IP addresses. This helps to not cause any interruption for the end-nodes.
Source:
https://www.htshosting.org/knowledge-base/server/100/what-is-a-dhcp-server
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