Dhcp
- 1. 70-291: MCSE Guide to Managing a Microsoft Windows Server 2003 Network Chapter 4: Dynamic Host Configuration Protocol
- 2. Objectives Outline the benefits of using DHCP Describe the DHCP lease and renewal process Install and authorize the DHCP service Configure DHCP scopes Create DHCP reservations for client computers Configure DHCP options Understand and describe the purpose of a DHCP relay Install and configure a DHCP relay
- 3. DHCP Overview Used to automatically deliver IP addressing Reduces the amount of time you spend configuring computers on your network Used by default unless you specify otherwise The ipconfig /all command will indicate whether the configuration came from a DHCP server computer
- 6. Leasing an IP Address An IP address is leased during the boot process The overall process is composed of four broadcast packets: DHCPDISCOVER DHCPOFFER DHCPREQUEST DHCPACK
- 7. Leasing an IP Address (continued) Any DHCP server that receives the DHCPDISCOVER packet responds with a DHCPOFFER packet The DHCP client responds to the DHCPOFFER packet it receives with a DHCPREQUEST packet A DHCPACK packet indicates confirmation that the client can use the lease Once DHCPACK is received, the client can start using the IP address and options in the lease
- 8. Leasing an IP Address (continued)
- 9. Renewing an IP Address The IP address can either be permanent or timed A permanent address is never reused for another client Timed leases expire after a certain amount of time Windows clients attempt to renew their lease after 50% of the lease time has expired A DHCP server may either honor or reject a renew request
- 10. Renewing an IP Address (continued)
- 11. Installing and Authorizing the DHCP Service A DHCP service must be authorized after installation
- 12. Installing the DHCP Service DHCP is a standard service It is included in Windows Server 2003 It is not installed as part of a default installation
- 13. Installing the DHCP Service (continued)
- 14. Activity 4-1: Installing DHCP Objective: Install DHCP on Windows Server 2003 Make sure your network connection is statically configured Install the service using the Add/Remove Windows Components utility
- 15. Authorizing the DHCP Service Unauthorized DHCP servers can hand out bad information DHCP will not start unless authorized If Active Directory is used, authorization takes place in Active Directory DHCP servers are automatically authorized under certain conditions
- 16. Authorizing the DHCP Service (continued)
- 17. Authorizing the DHCP Service (continued)
- 18. Activity 4-2: Starting an Authorized DHCP Server Objective: View the results of starting a DHCP server that does not participate in an Active Directory domain Check to make sure the service is running Check out any relevant events using the System Log
- 19. Activity 4-3: Installing the Active Directory Service Objective: Install the Active Directory service on your computer and participate in an Active Directory domain Use the dcpromo utility Select “domain controller for a new domain” Select “domain in a new forest” Continue through the resulting dialogs
- 20. Activity 4-4: Starting an Unauthorized DHCP Server Objective: View the results of starting an unauthorized DHCP server View the System Log to see the result of starting an unauthorized DHCP server
- 21. Activity 4-5: Authorizing a DHCP Server Objective: Authorize a DHCP server in Active Directory Go to the DHCP snap-in and choose the activate option
- 22. Configuring DHCP Scopes Scope defines a range of IP addresses Each scope is configured with: Description Starting IP address Ending IP address Subnet mask Exclusions Lease duration Two strategies exist for defining the starting and ending IP addresses Allow all and exempt the few static addresses Use only the addresses not already in use
- 23. Configuring DHCP Scopes (continued)
- 24. Configuring DHCP Scopes (continued) Exclusions are used to prevent some IP addresses from being handed out dynamically Lease duration defines how long client computers are allowed to use an IP address Default lease duration is eight days A scope must be activated before the DHCP service can begin using it
- 25. Activity 4-6: Creating a Scope Objective: Create a scope to distribute IP addresses to client computers Manually enter the IP configuration settings as directed by the text Create a new scope using the configuration settings provided
- 26. Activity 4-7: Activating and Testing a Scope Objective: Activate a DHCP scope, and then test it with a partner One person will activate the scope created in the previous activity Another person will try to obtain an automatic IP address from the server
- 27. Superscopes Used to combine multiple scopes into a single logical scope Allows multiple scopes to be treated as a single scope If a superscope is used, then the DHCP server offers only one lease as opposed to multiple leases
- 29. Activity 4-8: Configuring a Superscope Objective: Combine two scopes into a single logical unit using a superscope First, create a second scope in addition to the scope already created in a previous activity Create a superscope to encompass the two scopes Use the DHCP snap-in for this activity
- 30. Activity 4-9: Deleting a Superscope Objective: Delete a superscope, leaving each scope independent Make sure you delete the superscope without deleting the subscopes
- 31. Multicast Scopes Used to deliver multicast addresses to applications that require it Multicast addresses are used to deliver packets to groups of computers Start and end IP addresses define the range of addresses that can be handed out by DHCP servers TTL defines the number of routers through which a multicast packet can move
- 32. Multicast Scopes (continued) Exclusions define addresses that should not be handed out Lease duration defines the length of time that an application can use a multicast address Default lease length is 30 days
- 33. Activity 4-10: Creating a Multicast Scope Objective: Create a multicast scope to deliver multicast addresses to applications Setting up a multicast scope is very similar to setting up any other scope Set the scope configuration to that specified in the text
- 34. Activity 4-11: Deleting a Multicast Scope Objective: Delete a multicast scope Right click on the scope and issue the delete command
- 35. Creating DHCP Reservations Reservations are used to hand out a specific IP address to a particular client Useful when delivering IP addresses to devices that would normally use static addresses Can also be beneficial when firewalls are in place Reservations are created based on MAC addresses
- 36. Creating DHCP Reservations (continued)
- 37. Activity 4-12: Creating and Testing a Reservation Objective: Create a DHCP reservation, and test it with a client Configure the server to reserve an IP address for a client machine Test to see if the client machine picks up the reserved address
- 38. Configuring DHCP Options DHCP can hand out a variety of other IP configuration options It is common that all workstations within an entire organization use the same DNS servers DNS is often configured at the server level
- 39. Configuring DHCP Options (continued)
- 40. Configuring DHCP Options (continued)
- 41. Activity 4-13: Setting Server Options Objective: Set the DNS server option for a DHCP server Check 006 DNS servers option Add the IP address x.0.0.250
- 42. Activity 4-14: Setting Scope Options Objective: Set the default gateway in the scope options Use the DHCP snap-in to complete this activity
- 43. Activity 4-15: Testing Server & Scope Options Objective: Activate a DHCP scope, and then test it with a partner to ensure that scope options are handed out Activate a DHCP scope Configure a client to access the server Check the default gateway and DNS settings to find out whether or not the configurations entered in previous activities were done correctly
- 44. Vendor and User Classes Used to differentiate between clients within a scope Vendor classes are based on the operating system User classes are defined based on network connectivity or the administrator You can use the ipconfig /setclassid command to set the DHCP user class ID
- 45. Vendor and User Classes (continued)
- 46. Vendor and User Classes (continued)
- 47. Configuring a DHCP Relay DHCP packets cannot travel across a router A relay agent is necessary in order to have a single DHCP server handle all leases Relay agents receive broadcast DHCP packets and forward them as unicast packets to a DHCP server The DHCP relay cannot be installed on the same server as the DHCP service
- 48. Configuring a DHCP Relay (continued)
- 49. Configuring a DHCP Relay (continued)
- 50. Activity 4-16: Configuring a DHCP Relay Objective: Uninstall the DHCP service from your computer and configure it as a DHCP relay Uninstall the DHCP service Configure the computer as a relay by using the Routing and Remote Access tool provided in Windows
- 51. Summary DHCP dynamically assigns IP address information to clients on a network The DHCP lease process is composed of four packets: DHCPDISCOVER DHCPOFFER DHCPREQUEST DHCPACK A DHCP client attempts to renew its lease at 50%, 87.5%, and 100% of the lease time The commands ipconfig /release and ipconfig /renew can be used to release and renew DHCP leases
- 52. Summary (continued) If the Active Directory service is present on your network, each DHCP server must be authorized in Active Directory to lease addresses to clients A scope defines a range of IP addresses that are leased to clients A superscope combines two scopes into a single logical unit to service network segments with two subnets
- 53. Summary (continued) An exclusion in a scope can stop a DHCP server from handing out specific addresses A reservation allows you to give a specific workstation a defined IP address by tying the DHCP lease to the MAC address of the client Vendor and user classes can be used to configure some client computers with different options, depending on the class to which they belong A DHCP relay agent is required on each network that requires IP configuration from a DHCP server across a router