Transcript Chapter 1
Configuring and Managing the DHCP Server Role
DHCP overview
RARP – one of the first ways to assign addresses
BOOTP – Another legacy way to assign addresses. Still
had manual aspects to it.
DHCP – Based heavily off of BOOTP, but it is all
dynamic.
Centralized administration
Dynamic host configuration
Seamless
Flexibility and scalability
How DHCP works
Functions on the Application layer of OSI
Uses UDP broadcast messages
DHCP message Types
DHCPDISCOVER – sent by clients via broadcast to locate
a DHCP Server.
DHCPOFFER – Sent by DHCP server to client in response
to DHCPDISCOVER along with offered configuration
parameters.
DHCPREQUEST - Sent by client to signal acceptance of
offered address and parameters.
DHCP Messages contd.
DHCPDECLINE - Sent by client informing the server
the offered IP address has been declined.
DHCPACK – Sent by server to confirm IP address.
DHCPNACK – Sent by server to deny the clients
DHCPREQUEST.
DHCPRELEASE – sent by client relinquishing IP
address and canceling the remaining lease.
DHCPINFORM – sent from client to ask for additional
configuration parameters.
Putting the Messages to Work.
Putting the Messages to Work
The client will perform the initial process in the
following situations:
The very first time the client boots
After releasing its IP address
After receiving a DHCPNACK message
Other situations, such as renewing, the process will be
different. Refer to Page 40-41 of the reading.
Using the DHCP Relay Agent
Because DHCP uses broadcast messages you can not
use DHCP across multiple subnets.
To pass DHCP messages through the router it must be
RFC 1542 compliant.
If the router is not RFC 1542 compliant you can install
the DHCP relay agent.
The relay agent will forward messages to the DHCP
server.
Authorizing a DHCP Server
You must authorize a DHCP server in Active Directory
before you can issue leases to clients.
In a workgroup environment this does not need to be
done.
To authorize go into the DHCP console and choose to
authorize.
Configuring DHCP Scopes
Scope – the addresses that able to be assigned
192.168.1.1/24 through 192.168.1.254/24 is and example
Exclusion range – used to define addresses within the
scope that will NOT be given out to clients.
Available Address Pool – after all ranges and exclusion
are defined the remaining addresses are referred to
this.
Configuring a DHCP Reservation
A reservation allows you to specify a specific address
for a host.
Ensures the host will always have that address, sort of
like assigning a static address
The host’s MAC address is used to make the
reservation
Configuring DHCP Options
Options are additional client-configuration
parameters
4 types
Server options – apply to all clients of the DHCP server
Scope options – apply to all clients within a scope
Class options – provide DHCP parameters to DHCP clients
based on type
Client options – apply to individual clients. Client options
override all other options
Managing the DHCP Database
Backup and Restore
Reconciliation – verifies DHCP database against
registry values. After restore.
Compacting the database –optimizes database and
reclaims unused space.
Removing the database
You Learned
DHCP is a simple, standard protocol that makes
TCP/IP network configuration much easier for
the administrator by dynamically assigning IP
addresses and providing additional configuration
information to DHCP clients automatically.
Additional configuration information is provided
in the form of options and can be associated
with reserved IPs to a vendor or user class, to a
scope, or to an entire DHCP server.
Lesson 3
You Learned (cont.)
Because DHCP is a key component in your
organization, you must manage and monitor it.
DHCP management consists of backing up and
restoring the database as well as reconciling,
compacting, and, in some cases, removing the
database.
Lesson 3