Dynamic Host Configuration Protocol

Microsoft Server 2008 R2

Dynamic Host Configuration Protocol

• MAC Address• IP Addressing• DHCP Client• DHCP Server• Scope• Exclusion Range• Reservations• Netsh

HISTORY OF DHCP

THE ROLE OF DHCP

• Dynamically assigns TCP/IP addresses• Dynamically assigns TCP/IP configuration

information• Simplifies network administration

DYNAMIC VERSUS MANUAL TCP/IP ADDRESS ASSIGNMENT

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IP addresses entered manuallyon each client computer

IP addresses are supplied auto-matically to client computers

Possibility of entering incorrector invalid IP address

Ensures that client always usescorrect configuration information

Incorrect configuration canlead to communicationand network issues

Client configuration updatedautomatically to reflect network

changes

Administrative overload onnetworks on which computersare frequently moved

Elimination of source of networkproblems

Ethernet Address and IP address

• Each machine has an Ethernet address and IP address– Ethernet is a unique 48 bit address

• Also known as MAC (media access control) addresses

Ethernet Address and IP Address

• Can also view the MAC address by typing:– C:\>ipconfig /all– Start->run->msinfo32 <enter>

IP Addressing Rules and Concepts

• Addresses you cannot assign– Default route address: 0.0.0.0– Loopback address: 127.0.0.1– Network number: 172.17.13.0– IP Broadcast address: 172.17.13.255

Dynamic Host Configuration Protocol

• Used for manageability and automation of IP address assignment on networks.– Ie. ISP’s use

DHCP when you establish connection.

Scopes and Superscopes

• When configuring DHCP, the first step is to create a range of addresses that will be managed. This is called a scope.

• A single DHCP server can service more than one subnet by assigning a scope to each subnet.

• You can create a superscope to service more than on range of IP’s on the same segment.

DHCP MESSAGE TYPES

Used by clients to obtain additional TCP/IP addresses

DDHHCCPP MMeessssaaggee TTyyppee DDeessccrriippttiioonnDHCPDISCOVERUsed by clients to request configuration parameters

from a DHCP serverDHCPOFFER Used by servers to offer IP addresses to requesting

clientsDHCPREQUESTUsed by clients to accept or renew IP address

assignment and to decline unaccepted serversDHCPDECLINEUsed by clients to reject an offered IP addressDHCPACK Used by servers to acknowledge a client’s

acceptance of an offered IP addressDHCPNACK Used by servers to reject a client’s acceptance of an

offered IP addressDHCPRELEASEUsed by clients to terminate an IP address leaseDHCPINFORM

THE INITIAL DHCP LEASE PROCESS

DHCP LEASE RENEWAL PROCESS

WHAT IS A DHCP RELAY AGENT?

Leases, client options exclusions and reservations

• A lease determines how long the client will maintain the same IP address before it is issued a new lease of another IP address

• Client options are configured during the setup or after. They can range from simply setting the default gateway, DNS and WINS servers to Network Time Servers and NetBios Settings

• Exclusions are IP Addresses within the scope that you do not want assigned dynamically. For instance you may statically assign your server’s IP address and do not want that assigned to another machine. What would happen if it did assign it’s own IP address?– A single exclusion can be created or a range of exclusions

• Reservations ensure that the same MAC gets the same ip address every time. Reservations are created within the scope.

DHCP Management Console

WHAT IS A DHCP SCOPE?

WHAT IS A DHCP SCOPE?

WHAT ARE DHCP CLIENT RESERVATIONS?

Client reservations permanently reserve a specific address for a specific client.

Manually Renewing/ReleasingIPCONFIG /RELEASE Releases IP Address configuration and

lease

IPCONFIG /RENEW Request to renew same IP address or new IP Address

Questions