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.Building a SubnetBuilding a subnet is not too tricky.However, there are a couple of things that you will need to understand: the math behind network masks and the reserved IPs that you cannot use for a machine.The main thing you must decide is the number of segments you want to create.Subnetting works by specifying a different network mask from the default.The network mask specifies how many bits of the IP address belong to the network portion of the address.However many bits are left can be used for the host portion of the address.Table 12.4 lists the default network mask for each address class.Table 12.4.Default network masks.Address ClassDefault MaskA255.0B128.0-191.255C192.0-223.255.255Some of the octets represent network numbers others represent host numbers.Each octet represents a function of the network mask.A mask is simply a binary number that specifies which bits belong to the network and which bits belong to the host portion.Bits that are "on" (represented by 1) will be used for network address.For example, if you have an IP, such as 204.95.222.100, and the mask for this IP is 255.255.255.0, you can determine that the host portion can use all bits in the last octet; that amounts to 256 unique values ranging from 0-255.I find it easier to work with masks in binary:204.95.222.100: 11001100.01011111.11011110.01100100255.255.255.0: 11111111.11111111.11111111.00000000In the next example the mask was set to 255.255.255.128:204.95.222.100: 11001100.01011111.11011110.01100100255.255.255.128: 11111111.11111111.11111111.10000000This mask yields an extra bit for the network address (shown in bold).This means that you can have two subnets, and the host portion can use 7 bits, or 127 unique addresses, for each of the subnets.Caching Proxy Servers: Reducing the Bandwidth You ConsumeCaching proxy servers can be a powerful tool in your arsenal to increase the performance of your internal Web traffic.While originally developed as a way of allowing access to the Web through a firewall, proxy servers can also be used to reduce the traffic your organization generates to popular Web sites.Versions of Apache, beginning with 1.1, include a caching proxy server module that enables Apache to function as a caching proxy server.What Is a Proxy Server?A proxy server is a Web server that sits between a local client and an external Web server.It acts as an intermediary to the client and fetches information from other Web servers.Instead of a client connecting to a server on the Internet directly, it establishes a connection with a proxy server in the user's local network.The proxy server then retrieves the resources requested and serves them to the client as if the resources were its own.Besides negotiating a transaction for a client, proxy servers usually cache data they receive from other servers.Over time this cache will grow rich in pages from the most popular destinations on the Internet, allowing subsequent requests to be served from the local proxy.Instead of each request consuming your WAN bandwidth, subsequent requests to the same URL are served from the cache, locally and at LAN speeds.This virtually eliminates the bulk of the traffic to previously contacted sites and improves access times dramatically.This functionality has the effect of freeing bandwidth that would have been used to download duplicate information for other purposes, such as to serve your company's pages to outside users.If your connection to the Internet is not very fast, a catching proxy server can help you enhance your access to some of the most frequented sites on the Internet.Obviously, performance enhancements you obtain from a cache will depend on the richness of the cache, the surfing patterns of your users, and the amount of disk resources that you are willing to dedicate for this purpose.Overall, dedicating a caching server in your organization may provide many potential benefits to warrant its deployment.Setup of a proxy is not complicated and requires very little administrative time.Content TuningSo far, most of the issues I have talked about revolve around the software and hardware behind the server, but it is worth mentioning that there is one more way you can optimize performance.The less bandwidth that your content requires for transmission, the more quickly transfers will occur.Organizing and breaking your documents into smaller pieces will help tremendously
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