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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.

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.

The Top Virtually Bug-free Free Email Services on the Net Virtually bug-free e-mail services are available actually from several places. Many of these service providers are big names, known by many, especially Internet users. The difference between the different e-mail providers lies in several things. These differences include but are not limited to plenty storage space, effective spam filtering, a fast user-friendly interface, desktop e-mail program access and much more. Currently in the United States and the rest of the world, the best offer for free e-mail comes from Gmail. Gmail is part of the Google business enterprise (the search engine most of us know) and offers the most features and storage space for their users for free. With virtually unlimited storage capacity for e-mails, a user never has to delete any e-mails of the server and can collect all the messages. Gmail offers a simple user-friendly interface, which also includes an excellent search function that lets a user find messages instantly and precisely. Another great feature of gmail is the POP and IMAP access features. This gives the user the possibility to download the e-mail from the server with any e-mail program that the user generally would use. The program can then also automatically download the e-mails into the program ready for the user to read. Gmail is funded by displaying advertising next to the e-mails read. Next on the worldwide list would be GMX, a German provider that offers many of the features gmail offers, but with limited storage space. This program also has the POP feature and can therefore be used in conjunction with any of the common available PC e-mail programs. Right after gmail it is one of the most reliable e-mail services, but unfortunately they discontinued the English user face and only offer a German version now. Thereafter on the top free e-mail services providers is AIM Mail. It is the free web-based service from AOL. Like gmail it offers virtually unlimited online storage, excellent spam protection and a simple, easy to use interface. Unfortunately, AIM Mail lacks proper productivity, such things as labels, smart folders and message threading is not available. AIM Mail also offers a very functional POP and IMAP access. Yahoo! Mail would be the next e-mail service that should be mentioned on the list of the top virtually bug-free services on the Internet. Yahoo also offers virtually unlimited storage space for e-mails and a few other nice features, such as Short message services for texting to friends and family, instant-messaging features for the internet and up to date news feeds. What Yahoo! mail lacks is a really good spam filter. It offers a spam filter, but it is not effective enough. Also nice to have would be labeling options as well as smart folders. The Yahoo! Interface is just as easy and user-friendly as the other providers and fairly reliable. To complete the list we need to mention the following three services, Inbox.com, FastMail and Hotmail. Inbox.com offers e-mail users 5 GB of free space to store e-mail online. Despite the limited space, this service is outstanding due to its high-speed accessibility. Web access and POP access are very fast and even the search functions are faster than with most other services on the market. The drawbacks of Inbox.com are the missing IMAP access, only POP is provided and the organizing of mail is slightly unorganized due to missing smartfolder technology. FastMail on the other hand offers users only IMAP. It has many useful features and has one of the best web-based e-mail interfaces. It also generally displays fewer ads then the other services do. And lastly, Live Hotmail should be mentioned here, since most PC users that have a Windows based operating system will have heard of hotmail. This program offers 5 GB of storage for e-mails online. It has a fast search option, a solid security feature and the interface is as easy as the ones users are used to on their desktop. Even though security is great, the spam filter is not quite as effective as some of the other e-mail providers. Also missing with this provider is the POP and IMAP access as well as smartfolders and other great e-mail organizing features.