Planning the Network Topology

EXAM 70-293 OBJECTIVE 2, 2.1, 2.1.2, 2.2

The next phase in planning your TCP/IP infrastructure is planning the IP routing solution to manage the traffic on your network. This will depend on the physical location of your equipment and users, as well as on how you want to distribute the addresses. When your implement your strategy, you will also need to determine how the hosts on your network will resolve host names and implement the necessary services to provide that functionality. You will need to identify where the services such as DHCP, WINS, DNS, and so on must exist in your network to function properly and reduce the network bandwidth utilization.

Analyzing Hardware Requirements

Before you implement your network topology, you should identify the hardware needs. For each physical location, you will need to provide some sort of routing. You might need to implement a WAN solution using a T1 line, which also requires special hardware. You will need DHCP servers at each location or a DHCP relay agent. You will need to provide some form of name resolution, most likely DNS and possibly WINS. Depending on traffic and if you have a large number of users, you may decide to install switches to help manage network traffic.

For a DHCP server, the two major factors that affect performance are the amount of physical random access memory (RAM) and the speed of the disk input/output (I/O). You should always provide the largest amount of RAM possible and the fastest disk I/O for the best performance on a DHCP server. The same rules apply for WINS and DNS servers, although DNS is more dependent on network bandwidth. In any case, frequent zone updates require more RAM for better performance.

If you are using Active Directory (AD) DNS, there are other considerations related to AD, such as:

• Increased network utilization due to dynamic DNS updates related to DCHP integration and WINS reverse lookups

• Increased RAM requirements due the increased data volume

Planning the Placement of Physical Resources

EXAM 70-293 OBJECTIVE 2.2.1

The quantity of data and the type of network traffic will affect the location of IP resource servers in your enterprise. If the WAN link is slow, you might want to place DNS caching servers at each location to reduce WAN traffic related to DNS resolution. You might also consider providing a DNS server at each location to provide redundancy. In addition, by creating an AD integrated primary zone, you will allow clients to update their resource records locally. Defining which DNS servers can act as forwarders and perform iterative queries will help manage the Internet traffic.

You should also provide a DHCP server at each location. When you have multiple DHCP servers on your network, use the 80/20 rule to balance the load on the subnet: 80 percent of the scope will be on the primary server, with 20 percent on the other server. The DHCP server must have an interface on each network for which it has a scope defined, or you must locate a DHCP relay server on the same subnet as the DHCP clients.

If you implement WINS, you will need to examine the quantity of data replicated between WINS servers and the cost of WINS reverse lookups from DNS servers. You should minimize the number of WINS servers you implement in order to minimize the impact of WINS replication traffic on your network.

Use the Help and Support Center on Windows Server 2003 to see examples of performance statistics in a high traffic environment to help you gauge your enterprise needs.