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
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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