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Web Hosting - The Internet and How It Works In one sense, detailing the statement in the title would require at least a book. In another sense, it can't be fully explained at all, since there's no central authority that designs or implements the highly distributed entity called The Internet. But the basics can certainly be outlined, simply and briefly. And it's in the interest of any novice web site owner to have some idea of how their tree fits into that gigantic forest, full of complex paths, that is called the Internet. The analogy to a forest is not far off. Every computer is a single plant, sometimes a little bush sometimes a mighty tree. A percentage, to be sure, are weeds we could do without. In networking terminology, the individual plants are called 'nodes' and each one has a domain name and IP address. Connecting those nodes are paths. The Internet, taken in total, is just the collection of all those plants and the pieces that allow for their interconnections - all the nodes and the paths between them. Servers and clients (desktop computers, laptops, PDAs, cell phones and more) make up the most visible parts of the Internet. They store information and programs that make the data accessible. But behind the scenes there are vitally important components - both hardware and software - that make the entire mesh possible and useful. Though there's no single central authority, database, or computer that creates the World Wide Web, it's nonetheless true that not all computers are equal. There is a hierarchy. That hierarchy starts with a tree with many branches: the domain system. Designators like .com, .net, .org, and so forth are familiar to everyone now. Those basic names are stored inside a relatively small number of specialized systems maintained by a few non-profit organizations. They form something called the TLD, the Top Level Domains. From there, company networks and others form what are called the Second Level Domains, such as Microsoft.com. That's further sub-divided into www.Microsoft.com which is, technically, a sub-domain but is sometimes mis-named 'a host' or a domain. A host is the name for one specific computer. That host name may or may not be, for example, 'www' and usually isn't. The domain is the name without the 'www' in front. Finally, at the bottom of the pyramid, are the individual hosts (usually servers) that provide actual information and the means to share it. Those hosts (along with other hardware and software that enable communication, such as routers) form a network. The set of all those networks taken together is the physical aspect of the Internet. There are less obvious aspects, too, that are essential. When you click on a URL (Uniform Resource Locator, such as http://www.microsoft.com) on a web page, your browser sends a request through the Internet to connect and get data. That request, and the data that is returned from the request, is divided up into packets (chunks of data wrapped in routing and control information). That's one of the reasons you will often see your web page getting painted on the screen one section at a time. When the packets take too long to get where they're supposed to go, that's a 'timeout'. Suppose you request a set of names that are stored in a database. Those names, let's suppose get stored in order. But the packets they get shoved into for delivery can arrive at your computer in any order. They're then reassembled and displayed. All those packets can be directed to the proper place because they're associated with a specified IP address, a numeric identifier that designates a host (a computer that 'hosts' data). But those numbers are hard to remember and work with, so names are layered on top, the so-called domain names we started out discussing. Imagine the postal system (the Internet). Each home (domain name) has an address (IP address). Those who live in them (programs) send and receive letters (packets). The letters contain news (database data, email messages, images) that's of interest to the residents. The Internet is very much the same.

Web Hosting - Sharing A Server – Things To Think About You can often get a substantial discount off web hosting fees by sharing a server with other sites. Or, you may have multiple sites of your own on the same system. But, just as sharing a house can have benefits and drawbacks, so too with a server. The first consideration is availability. Shared servers get re-booted more often than stand alone systems. That can happen for multiple reasons. Another site's software may produce a problem or make a change that requires a re-boot. While that's less common on Unix-based systems than on Windows, it still happens. Be prepared for more scheduled and unplanned outages when you share a server. Load is the next, and more obvious, issue. A single pickup truck can only haul so much weight. If the truck is already half-loaded with someone else's rocks, it will not haul yours as easily. Most websites are fairly static. A reader hits a page, then spends some time skimming it before loading another. During that time, the server has capacity to satisfy other requests without affecting you. All the shared resources - CPU, memory, disks, network and other components - can easily handle multiple users (up to a point). But all servers have inherent capacity limitations. The component that processes software instructions (the CPU) can only do so much. Most large servers will have more than one (some as many as 16), but there are still limits to what they can do. The more requests they receive, the busier they are. At a certain point, your software request (such as accessing a website page) has to wait a bit. Memory on a server functions in a similar way. It's a shared resource on the server and there is only so much of it. As it gets used up, the system lets one process use some, then another, in turn. But sharing that resource causes delays. The more requests there are, the longer the delays. You may experience that as waiting for a page to appear in the browser or a file to download. Bottlenecks can appear in other places outside, but connected to, the server itself. Network components get shared among multiple users along with everything else. And, as with those others, the more requests there are (and the longer they tie them up) the longer the delays you notice. The only way to get an objective look at whether a server and the connected network have enough capacity is to measure and test. All systems are capable of reporting how much of what is being used. Most can compile that information into some form of statistical report. Reviewing that data allows for a rational assessment of how much capacity is being used and how much is still available. It also allows a knowledgeable person to make projections of how much more sharing is possible with what level of impact. Request that information and, if necessary, get help in interpreting it. Then you can make a cost-benefit decision based on fact.

Web Hosting - Redundancy and Failover Among the more useful innovations in computing, actually invented decades ago, are the twin ideas of redundancy and failover. These fancy words name very common sense concepts. When one computer (or part) fails, switch to another. Doing that seamlessly and quickly versus slowly with disruption defines one difference between good hosting and bad. Network redundancy is the most widely used example. The Internet is just that, an inter-connected set of networks. Between and within networks are paths that make possible page requests, file transfers and data movement from one spot (called a 'node') to the next. If you have two or more paths between a user's computer and the server, one becoming unavailable is not much of a problem. Closing one street is not so bad, if you can drive down another just as easily. Of course, there's the catch: 'just as easily'. When one path fails, the total load (the amount of data requested and by how many within what time frame) doesn't change. Now the same number of 'cars' are using fewer 'roads'. That can lead to traffic jams. A very different, but related, phenomenon occurs when there suddenly become more 'cars', as happens in a massively widespread virus attack, for example. Then, a large number of useless and destructive programs are running around flooding the network. Making the situation worse, at a certain point, parts of the networks may shut down to prevent further spread, producing more 'cars' on now-fewer 'roads'. A related form of redundancy and failover can be carried out with servers, which are in essence the 'end-nodes' of a network path. Servers can fail because of a hard drive failure, motherboard overheating, memory malfunction, operating system bug, web server software overload or any of a hundred other causes. Whatever the cause, when two or more servers are configured so that another can take up the slack from one that's failed, that is redundancy. That is more difficult to achieve than network redundancy, but it is still very common. Not as common as it should be, since many times a failed server is just re-booted or replaced or repaired with another piece of hardware. But, more sophisticated web hosting companies will have such redundancy in place. And that's one lesson for anyone considering which web hosting company may offer superior service over another (similarly priced) company. Look at which company can offer competent assistance when things fail, as they always do sooner or later. One company may have a habit of simply re-booting. Others may have redundant disk arrays. Hardware containing multiple disk drives to which the server has access allows for one or more drives to fail without bringing the system down. The failed drive is replaced and no one but the administrator is even aware there was a problem. Still other companies may have still more sophisticated systems in place. Failover servers that take up the load of a crashed computer, without the end-user seeing anything are possible. In fact, in better installations, they're the norm. When they're in place, the user has at most only to refresh his or her browser and, bingo, everything is fine. The more a web site owner knows about redundancy and failover, the better he or she can understand why things go wrong, and what options are available when they do. That knowledge can lead to better choices for a better web site experience.