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Web Hosting - Bandwidth and Server Load, What's That?
Two key performance metrics will impact every web site owner sooner or later: bandwidth and server load.
Bandwidth is the amount of network capacity available, and the term actually covers two different aspects. 'Bandwidth' can mean the measure of network capacity for web traffic back and forth at a given time. Or, it sometimes is used to mean the amount that is allowed for some interval, such as one month. Both are important.
As files are transferred, emails sent and received, and web pages accessed, network bandwidth is being used. If you want to send water through a pipe, you have to have a pipe. Those pipes can vary in size and the amount of water going through them at any time can also vary.
Total monthly bandwidth is a cap that hosting companies place on sites in order to share fairly a limited resource. Companies monitor sites in order to keep one site from accidentally or deliberately consuming all the network capacity. Similar considerations apply to instantaneous bandwidth, though companies usually have such large network 'pipes' that it's much less common for heavy use by one user to be a problem.
Server load is a more generic concept.
It often refers, in more technical discussions, solely to CPU utilization. The CPU (central processing unit) is the component in a computer that processes instructions from programs, ordering memory to be used a certain way, moving files from one place to the next and more.
Every function you perform consumes some CPU and its role is so central (hence the name) that it has come to be used as a synonym for the computer itself. People point to their case and say 'That is the CPU'. But, the computer actually has memory, disk drive(s) and several other features required in order to do its job.
Server load refers, in more general circumstances, to the amount of use of each of those other components in total.
Disk drives can be busy fetching files which they do in pieces, which are then assembled in memory and presented on the monitor, all controlled by instructions managed by the CPU.
Memory capacity is limited. It's often the case that not all programs can use as much as they need at the same time. Special operating system routines control who gets how much, when and for how long, sharing the total 'pool' among competing processes.
So, how 'loaded' the server is at any given time or over time is a matter of how heavily used any one, or all, of these components are.
Why should you care?
Because every web site owner will want to understand why a server becomes slow or unresponsive, and be able to optimize their use of it.
When you share a server with other sites, which is extremely common, the traffic other sites receive creates load on the server that can affect your site. There's a limited amount you can do to influence that situation. But if you're aware of it, you can request the company move you to a less heavily loaded server. Or, if the other site (which you generally have no visibility to) is misbehaving, it's possible to get them moved or banned.
But when you have a dedicated server, you have much more control over load issues. You can optimize your own site's HTML pages and programs, tune a database and carry out other activities that maximize throughput. Your users will see that as quicker page accesses and a more enjoyable user experience.
Web Hosting - Domain Name Changes and How They Affect You New domain names are registered all the time, and ones previously registered expired. Sometimes that's the result of simple neglect. The owner of the name chose not to renew his or her ownership, so the name became available for someone else to use. In rare cases, a highly original mind managed to think of a new one. In the other common scenarios, someone chose to just let it go or sell it. When you choose to change your domain name, there are actually two separate steps involved: releasing the old name, and adopting the new one. But, just as the postal system can have difficulty forwarding your letters when you change your personal name, changing your domain name brings certain difficulties. One of the most prominent is the fact that any name change requires a change to thousands of DNS Servers around the globe. DNS (Domain Name System) is the set of software/hardware components that allows domain names to map to IP addresses. IP addresses are what are actually used 'under the covers' when one computer communicates with another. Note that there isn't always a 1:1 correspondence between a name and an IP address. One IP address can serve multiple domain names and one domain name can have multiple IP addresses. For the sake of simplicity, we'll stick to the common case here. DNS servers around the world maintain internal databases that match the name to an IP address. Not all servers have all pairs of names/addresses. A series of complex routines allows a request to be forwarded when the particular DNS server doesn't have a needed record. When you acquire a domain name that used to be associated with a given IP address, the odds of you acquiring the same IP address are extremely low. In the unlikely case, for example, that you acquired the domain name yahoo.com, you would almost certainly not get the IP address that was matched with it (unless you bought the Yahoo! company). So, as a result of the change, the name/IP address pair is no longer what it was. A similar circumstance exists when you retain your IP address, but want to change the domain name associated with it. In either case, the pairing has changed. The catch is this: when the change takes place, those DNS databases are not all updated instantaneously around the world. Even apart from the limited speed with which computers and networks operate, (and neglecting the human factor if/when the change is made manually to more than one server) the reason is something called caching. In order to communicate efficiently, DNS servers are designed to assume that changes will be relatively rare. Just as with the postal system, you don't move your address or change your name every minute. Since that's true, in general, the name/IP address pair is cached. A cache is a set of stored information that is reused so that fresh information doesn't have to be communicated with every request for a web page or data. A chain of DNS servers pass requests to the last known address. There is usually more than one system between your computer and the server you want to communicate with. Most of the time, that's your current name/address. When you change the name, that pair is no longer valid. In order to propagate the new name/address pair (so the terminology goes), that cache has to be refreshed. Something similar happens when you establish an entirely new name. That name is first associated with an IP address and that pair has to be communicated to DNS servers around the world in order for you to be able to reach any one of them at random. But DNS servers don't do that until they are requested to do so by your action of asking for information from a remote server. Because of that, but chiefly because of caching, it can take quite a while for the new pair to become known around the Internet. Caches can expire and get refreshed in a few minutes or a few hours. It varies. That time can be as short as an hour or less, if the path between your computer and the web server is very simple and only one DNS server needs to be updated. Or, it can take up to 48 hours or more. Though the 'official' range is often given by registrars as 24-48 hours, the average is closer to about six hours. But that's an average. The actual time in any given case can (and does) vary widely. In the meantime, a number of effects can occur. The most obvious is that, since the name/IP address pair can't be resolved properly, you don't reach the server you want. Your browser points to the old one (in the rare case it's still accessible by that name and address), or it simply reports there's no such name at that address. So, when registering a new name or buying an old one, you should establish the site, but not advertise it for at least a couple of days. Better to wait to get visitors than to turn them off by being 'not at home' when they call. Movie Copyright Law College Students Are Being Targeted For Breaking Movie Copyright Law Many people have taken up the hobby of downloading movies and songs on the Internet and sharing them with their friends and family online. However, this is direct violation of the movie copyright law. Not surprisingly, the biggest violators of the movie copyright law are students. It is not surprising that the movie industry sector is sending out copyright infringements claims to college universities around the country. One reason that college students may be the hardest hit when it comes to violations brought against them for infringing on movie copyright law is that they are not aware of how serious a crime it truly it. Many college students who have suits brought against them are shocked, to say the least. They question why they were not warned about the perils of downloading movies and songs online and passing them along to friends. However, with the rise of claims that are being handed down, no one can claim ignorance for much longer. Word is being spread near and far that if you are engaging in illegal downloading and/or sharing then you can be brought to court. College students are learning the hard way that it is against the law and in violation of the movie copyright law to share or download copyrighted material. Many colleges and universities are now stating in their handbooks that it is against the law and the university rules to illegally download movies, music and other forms of media online using a school computer. In addition to illegal downloading and sharing software, the files take up space on the computer systems and use a considerable amount of bandwidth. While most universities and colleges will not look at the content an individual has -- they can isolate and identify the individuals who are hogging up the bandwidth by using illegal file sharing software. The movie and music industries have stepped in and are demanding restitution for illegally downloaded movies, music and other forms of copyrighted media. They have detection agencies that have the technology to identify and trace copyright infringements straight to their source. Once the computer is located they can notify the university or the college that they are in violation. The university will be told that they have a copyright infringement claim against them. Based on the Digital Millennium Copyright Act once the computer is isolated Internet access is terminated to that computer and court proceedings can begin. Does this sound far fetched? Well, it is not. You should know that in April of 2003 four students were sued by Recording Industry Association of America. These students attended Princeton, Michigan Technical University and Rensselear Polytechnic Institute. One student alone had an estimated liability of $150 billion. When you consider that you can be charged $750 per song that is illegally downloaded, the total can add up fast! The good thing is the lawsuits against the college students were settled for amounts less than $20,000. That is not pocket change for college students – or anyone for that matter! Movies and music are meant to be enjoyed. However, illegally downloading movies and music is not much different than walking into a video store and sticking DVDs and CDs in your pocket. Be careful. You do not want to be caught violating the movie copyright law. |