About DHCP Reservations
Setting up DHCP Reservations
In
order to set up DHCP reservations, administrators use physical address of the
target DHCP client computer for which a particular IP address is to be
reserved. Administrators can know the physical address of the target computer
by either going to the computer physically, or by accessing it via Remote
Desktop feature and using IPCONFIG /ALL command. ARP command can also be used
to obtain the MAC address of the target computer using command line interface.
Once the physical (MAC) address of the target computer is obtained, it is then
specified in the DHCP Reservations option along with the desired IP address
that is to be mapped with it.
Where DHCP Reservations Are Used?
In
local area network, there might be times when administrators do not want to
assign static IP addresses even to the servers in order to reduce administrative
overhead. However, since the servers must always have a permanent IP address,
administrators can use DHCP reservation to reserve a particular IP address for
each server in the network. By doing so, administrators can eliminate the need
of assigning static IP addresses to the servers manually, hence reducing the
administrative overhead.
How DHCP Reservation Works?
Once
an IP address is reserved for a computer and the computer is powered on, it
broadcasts a DHCP Discover packet in the entire network. When the packet is
received by the DHCP server, the server looks for and identifies the MAC
address of the DHCP client computer (typically a dedicated server for some
other service in the network). Once the physical address of the client computer
is identified, the DHCP server looks in its reservation records and finds the
IP address that is kept reserved for it and assigns the address to the DHCP
client computer.
Set up DHCP Reservation for a Computer
To
set up DHCP reservation in Windows Server 2008 R2 for a DHCP client computer in
the network, administrators must follow the steps given as below:
1.
Go to the target DHCP client computer
and fetch its physical address by typing IPCONFIG /ALLcommand in
the command line interface and pressing Enter key.
2.
Log on to Windows Server 2008 R2 DHCP
Server computer with domain admin or enterprise admin account credentials on
which DHCP server role is installed.
3.
From the desktop screen click Start button.
4.
From the displayed menu, go to Administrative
Tools > DHCP.
5.
On DHCP snap-in, from
the console tree in the left pane, double-click to expand the DHCP server name.
6.
From the expanded list, go to IPv4 >
<DHCP scope name>.
7.
From the displayed list, right-click Reservations.
Right-click Reservations
8.
From the context menu that appears,
click New Reservation.
9.
On New Reservation box,
in the Reservation name field, specify a new reservation name.
10. In
the IP address field, type the IP address from the DHCP IP
address pool that is to be reserved for the target DHCP client computer.
New Reservation
11. In
the MAC address field, specify the physical address of the
target DHCP client computer that was retrieved earlier in step 1.
12. Click Add to
add the new reservation to the selected DHCP scope.
13. Once
added, click Close.
14. Close DHCP snap-in
when done.
