DHCP automates the allocation of IP addresses, subnet masks, default gateways, and other network configuration parameters. It uses four messages - DHCPDISCOVER, DHCPOFFER, DHCPREQUEST, DHCPACK - to allocate addresses dynamically or statically. DHCP can be designed for LANs, routed networks, and non-Microsoft clients. It enhances availability through features like superscopes across multiple servers and Windows Server 2003 clustering. Security involves authorizing servers, controlling access, and using firewalls. Performance is increased by shortening response times, distributing load across servers, and optimizing lease times.

1. Session 3 DHCP Network Design

2. TCP/IP works on four layers: Interface Internet Transport Application. The subnet mask displays only the network ID. Subnets can be created on a physical or logical basis. A secure network is one where data and resources are protected effectively. Review

3. Objectives Describe DHCP and its working Identify the requirements for a DHCP solution Identify DHCP design possibilities Secure the DHCP service Identify the methods to enhance the DHCP service

4. Dynamic Host Configuration Protocol (DHCP) Automates the allocation of: IP addresses Subnet mask Default gateway WINS server. IP address allocation takes place using four commands: DHCPDISCOVER DHCPOFFER DHCPREQUEST DHCPACK IP address allocation can be dynamic, automatic or manual IP addresses must be renewed periodically

5. Features of DHCP The features of DHCP are: RFC Compliance Integration with DNS and Active Directory Support for vendor specific options and Multicast addresses Integration of Routing and Remote Access

6. DHCP Design DHCP can be designed for: LAN Routed Networks Non-Microsoft Clients

7. DHCP Design for the LAN One DHCP server can support thousands of DHCP clients in a local area network

8. DHCP Design for the LAN Contd… In a single DHCP environment, one scope that contains the entire TCP/IP configuration required for that network, is defined for all the DHCP clients. In a multiple DHCP environment, we may need to define one superscope that includes all the scopes.

9. DHCP Design for Routed Network We have to make use of the DHCP relay agent to forward broadcast requests through the routers to the DHCP servers. DHCP client uses the dynamic host communication protocol to communicate with the DHCP relay agent. DHCP relay agent sends unicast packets to the DHCP server.

10. DHCP Relay Agent DHCP relay agent is used if: No DHCP server is available on that subnet DHCP relay agent can be run on available computers Routers do not support DHCP or BOOTP packets

11. DHCP Design for Non Microsoft Clients A network consists of Windows clients and non-Windows based clients. All the clients in the network may require dynamic IP address configuration

12. DHCP Design Enhancement To increase the availability of the DHCP server, we need to: Create superscopes on multiple DHCP servers Enable support for Windows Server 2003 clustering solution DHCP server

13. Superscopes on multiple DHCP servers Enables sharing of IP addresses and increase the availability of the DHCP service The load on the DHCP servers is distributed among all the DHCP servers and reduces redundancy by using distributed scopes

14. DHCP Server and Windows Server 2003 Clustering Provides immediate failover and the service is restarted when an event fails Provides quick restoration of failed server as only one DHCP database is referred to Enables elimination of distributed scope, which reduces overhead

15. Installing DHCP Installing DHCP involves: Installing and authorizing the DHCP service Creating and configuring the scopes to be used Setting up optional parameters Activating the scopes

16. DHCP Administration Security DHCP administrating can be secured by: Securing the DHCP service Identifying and stopping rogue DHCP servers Using a firewall

17. Securing DHCP We can provide security by: Authorizing the DHCP Server Controlling user access to the configuration files of the DHCP server

18. Authorization of DHCP Server There must be one DHCP server with the active directory enabled in the network. The active directory contains the list of authorized DHCP servers. When the other Windows Server 2003 DHCP servers start, they contact the Active Directory DHCP server, and are authorized to lease the IP addresses

19. Control User Access using Windows Server 2003 Groups DHCP administrators are special group that have permissions for DHCP administration. The DHCP Users and special local group permit Read Only access. An authorized user can gain access to information on a DHCP server by being a member of the special group. A user can be stopped from making any changes to the configuration

20. Rogue DHCP Servers An unauthorized or rogue DHCP server may cause the network to malfunction. Windows Server 2003 supports server authorization when DHCP service is installed. The DHCP service is shut down if the DHCP server is not authorized

21. DHCP in a Firewall Environment We can reduce unauthorized access by: Configuring the reserved IP address manually Extending the lease duration Reducing the available address range

22. DHCP Performance DHCP server performance can be increased by: Enhancing the single DHCP server’s response time Using multiple DHCP servers Modifying the DHCP lease time

23. Single DHCP Server We can improve the DHCP performance in Windows Server 2003 by: Using multiple CPUs so that the DHCP service can function faster using multithreading Enhancing the database so that the query response time can be the best possibl e We can improve the DHCP server response time by: Adding more than one CPU Adding enough memory Having high performance disks Having high bandwidth network card or many network cards

24. Multiple DHCP Servers We can enhance the performance of multiple DHCP servers by: Having distributed scopes so that the address range is divided between the servers Placing a DHCP server on the most populated subnet Placing DHCP servers on either side of the WAN link Having multi-homed DHCP servers so that network traffic across subnets is minimized

25. DHCP Server Lease Time If we reduce the lease time, the network traffic increases, though the IP address is released sooner. If we increase the lease time, the network traffic decreases and the IP address is released later.

26. Summary DHCP automates allocation of IP addresses and other networking information IP address allocation uses four commands: DHCPDISCOVER DHCPOFFER DHCPREQUEST DHCPACK DHCP can be designed for LANs, Routed Networks, and non-Microsoft clients

27. Summary Contd… DHCP can be secured by stopping rogue servers and using firewalls One DHCP server can support thousands of DHCP clients in a local area network DHCP client uses the dynamic host communication protocol to communicate with the DHCP relay agent DHCP relay agent sends unicast packets to the DHCP server

28. Summary Contd… Installing DHCP involves: Installing and authorizing the DHCP service Creating and configuring the scopes to be used Setting up optional parameters Activating the scopes DHCP administrating can be secured by: Securing the DHCP service Identifying and stopping rogue DHCP servers Using a firewall

29. Summary Contd… DHCP server performance can be increased by: Enhancing the single DHCP response time of the server Using multiple DHCP servers Modifying the DHCP lease time