In some areas they are different networks in the same building, we need a DHCP server to provide Ip address for the computers in this different networks. It is possible to configure DHCP server with multiple range of ip address.
Configuration Example
In the working example configuration shown below, the DHCP server host is only connected to the 192.168.0.0/24 IP subnet. DHCP clients in the ethernet network segment using a 192.168.2.0/24 IP subnet will be served IP configuration leases in the 192.168.2.100 – 192.168.2.200 range because the requests are relayed by the 192.168.2.1 DHCP Relay Agent (this DHCP Relay is assumed to already be present on the 192.168.2.0/24 subnet and configured to relay DHCP messages for this DHCP server).
Most significantly, a host previously connected to the 192.168.0.0/24 network, but later moved to the 192.168.2.0/24 network segment, will be forced to obtain a new IP configuration lease in the 192.168.2.100 – 192.168.2.200 range, so that it can function correctly on this separate network and IP subnet.
Example /etc/dhcpd.conf
ddns-update-style none;
default-lease-time 3600;
max-lease-time 7200;
authoritative;
log-facility local5;
subnet 192.168.0.0 netmask 255.255.255.0 {
range 192.168.0.100 192.168.0.200;
option domain-name-servers 192.168.0.2;
option routers 192.168.0.1;
}
subnet 192.168.2.0 netmask 255.255.255.0 {
range 192.168.2.100 192.168.2.200;
option domain-name-servers 192.168.2.2;
option routers 192.168.2.1;
}
Configure the DHCP Relay Agent
The DHCP Relay Agent (dhcrelay) allows for the relay of DHCP and BOOTP requests from a subnet with no DHCP server on it to one or more DHCP servers on other subnets.
When a DHCP client requests information, the DHCP Relay Agent forwards the request to the list of DHCP servers specified when the DHCP Relay Agent is started. When a DHCP server returns a reply, the reply is broadcast or unicast on the network that sent the original request.
The DHCP Relay Agent listens for DHCP requests on all interfaces unless the interfaces are specified in /etc/sysconfig/dhcrelay with the INTERFACES directive.
To start the DHCP Relay Agent, use the command service dhcrelay start
The DHCP Relay Agent (dhcrelay) allows for the relay of DHCP and BOOTP requests from a subnet with no DHCP server on it to one or more DHCP servers on other subnets.
When a DHCP client requests information, the DHCP Relay Agent forwards the request to the list of DHCP servers specified when the DHCP Relay Agent is started. When a DHCP server returns a reply, the reply is broadcast or unicast on the network that sent the original request.
The DHCP Relay Agent listens for DHCP requests on all interfaces unless the interfaces are specified in /etc/sysconfig/dhcrelay with the INTERFACES directive.
The DHCP Relay Agent (dhcrelay) allows for the relay of DHCP and BOOTP requests from a subnet with no DHCP server on it to one or more DHCP servers on other subnets.
When a DHCP client requests information, the DHCP Relay Agent forwards the request to the list of DHCP servers specified when the DHCP Relay Agent is started. When a DHCP server returns a reply, the reply is broadcast or unicast on the network that sent the original request.
The DHCP Relay Agent listens for DHCP requests on all interfaces unless the interfaces are specified in /etc/sysconfig/dhcrelay with the INTERFACES directive.
To start the DHCP Relay Agent, use the command service dhcrelay start
The DHCP Relay Agent (dhcrelay) allows for the relay of DHCP and BOOTP requests from a subnet with no DHCP server on it to one or more DHCP servers on other subnets.
When a DHCP client requests information, the DHCP Relay Agent forwards the request to the list of DHCP servers specified when the DHCP Relay Agent is started. When a DHCP server returns a reply, the reply is broadcast or unicast on the network that sent the original request.
The DHCP Relay Agent listens for DHCP requests on all interfaces unless the interfaces are specified in /etc/sysconfig/dhcrelay with the INTERFACES directive.
