Overview of DHCP Classes
DHCP classes
are the categories for which when DHCP client computers are configured, they
receive a different predefined set of DNS servers’ addresses, addresses of the
default gateways, etc. There are three types of classes that DHCP servers allow
administrators to work with. They are:
- Default Class
- User Class
- Vendor Class
User
and Vendor classes must be created manually by the DHCP administrators whereas
Default classes are created automatically as soon as the role of the DHCP
server is installed on the network operating systems. By default all DHCP clients
are configured as the default class clients and receive dynamic addresses as
per the default DHCP class scopes.
In
small-scale organizations and home environments, DHCP servers are installed
normally and no class oriented configurations are done. The reason behind this
is that by default all DHCP client computers belong to default DHCP class and
as soon as DHCP scopes are configured and the DHCP servers become ready to
assign dynamic addresses to the client computers, the DHCP clients start
receiving the IP addresses without any additional administrative overheads.
However, in order to allow DHCP servers to assign different sets of DNS and
default gateway addresses to the DHCP client computers, DHCP User or Vendor
classes must be created and the DHCP clients must be configured to obtain those
set of addresses from their respective DHCP classes. To do so, the
default class of the DHCP clients must be changed and the computers must be set
to User or Vendor classes.
Details About the 3 DHCP
Classes Are:
Default Class: This DHCP class is by default configured as soon as the DHCP server
role is installed on the network operating systems. After the
successful installation of DHCP server roles, administrators must create DHCP
scopes where they must specify a range of IP addresses along with the addresses
of the DNS servers and the default gateways. Since all DHCP client computers by
default belong to default DHCP class, they receive the set of addresses from
the default class only.
User Class: This DHCP class must be created manually by the administrators. User
class is created in the environments where a computer or a group of computers
is to be redirected to the different network or a specific computer by
assigning addresses of different DNS server and/or the default gateway. An
example can be of accounts department in an organization, computers of which
need to access highly sensitive information from file servers that are kept
isolated from the rest of the organization’s network. Since such file servers
may have different IP addresses that may belong to different network addresses
or different address classes altogether, creating User classes and specifying
addresses of DNS servers and default gateways that redirect the queries to the
sensitive and isolated file servers make the network setup quite efficient and
highly secured.
Vendor Class: This DHCP class works in the same manner as User class does, i.e. it
also provides a different set of address of DNS servers and default gateways to
the DHCP client computers. However, Vendor classes are created when a network setup has
multi-platform environment and the administrators want the DHCP client
computers running non-Microsoft operating systems to obtain a different set of
DNS and default gateway addresses. For example, in an organization some
computers have Microsoft Windows 7 installed on them and receive 192.168.11.1
as their DNS and default gateways. On the other hand, other computers have
Linux OS installed on them. A Vendor class for Linux can be created so that all
Linux clients can be assigned with different DNS and default gateway addresses,
e.g. 192.168.24.2.
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