Unlimited bandwidth (data transfer) on your web hosting account may sound like a great idea; no worrying about having to pay more when your site becomes popular, no concerns about people hotlinking images directly from your domain and using your transfer quota without your permission. Just upload your site and spend the rest of your time worrying about how to get visitors, right? Wrong. The truth is there are a number of reasons why unlimited transfer quotas are a bad thing, this article hopes to explain some of them.
Bandwidth is not free.
Even if you may get an unlimited supply from your web host, they have to pay for it. How they pay varies, sometimes they'll pay per gigabyte that their customers transfer, sometimes they'll pay for the speed of their connection (and the more customers transferring large amounts of data, the faster and more expensive connection they'll need). However the web host have it set up, there is no such thing as free bandwidth - they'll pay for it somehow.
Data transfer quotas are a way to limit usage of servers.
Even if the host has plenty of available bandwidth, each time your website transfers a file to one of your customers, their web server has to think for a split second about it. When this happens thousands of times a second over many different customer websites, the web server can get overloaded - this is similar to when you have lots of programs running on your PC and it gets slow. The busier the websites, the worse the problem is. It costs money to upgrade and purchase additional servers, so it costs your web host more, the busier your website is. Data transfer usage is directly related to the load you place on your web host's server; the more visitors to your website you get, the more bandwidth you will use, the more load you will place on their server and the more they will need to upgrade their servers to cope.
Bandwidth quotas are therefore a way to restrict both your actual data transfer usage and the load you place on your web host's server, both of these things directly cost your web host money.
Web hosts that offer unlimited bandwidth are banking on the fact that the majority of their customers will not use much of their bandwidth. This is certainly the case for most web hosts (including Digital Crocus). However, unlimited bandwidth web hosts attract customers with websites that use a lot of bandwidth - it's a very attractive option to the owner of a busy website that consumes lots of bandwidth to host it on a web host that do not limit their bandwidth usage. Most often if a website is very bandwidth-hungry, it means the website is popular and profitable and the owner will be willing to pay the bandwidth costs. There are cases where a website will be very bandwidth-hungry but not hugely profitable; this is true of illegal music/software/game download sites and spam sites. Would you like to share a web server with spammers and pirates?
If my web host are willing to offer me unlimited bandwidth then surely they're prepared to pay for the costs of additional bandwidth and upgrade their servers when necessary to cope with the load? Well, not necessarily.
Fair usage policies are a way to obscure the fact that there is a limit on how much bandwidth you use, without telling you what that limit is.
Most unlimited bandwidth web hosts will have a fair usage policy hidden somewhere deep within their terms of service. This is really just a marketing technique to convince you that you're getting unlimited bandwidth when you're not. The fair usage policy gives the web host the right to discontinue your account if they consider your use of their service "unfair". How they define "unfair" is arbitrary but will always involve drawing a line somewhere on the amount of bandwidth you can use. They will not tell you where they draw this line, because then they'd be setting a limit on bandwidth usage and would no longer be able to claim "unlimited bandwidth". When you reach this invisible line, the web host will often discontinue your service completely rather than offer you an upgrade to a package with greater bandwidth, in some cases with little or no notice at all.
Which would you rather; knowing exactly when you're going to have to pay more for bandwidth and having the option to upgrade with zero interruption to your web hosting service, or not having a clue when your host are going to deem your usage "unfair" and risking significant downtime as you have to transfer your site to another web host?
Web hosts are not like restaurants, if you go to an all-you-can-eat restaurant and they decide you've had enough before you're ready, it's not the end of the world, you can always go elsewhere without much hassle. If you go to an unlimited bandwidth web host and they decide you've had enough, your website may be taken offline and you may lose visitors, customers and money - if you've got a very profitable website, you could stand to lose significant amounts of money while you sort out a new web host.
Some unlimited bandwidth hosts do not have fair usage policies, but these are often newly founded companies who have just recently bought a top of the range server and are still well within the bandwidth limits imposed by their providers. If you get an account with them at the right time, you may find that you get a great service, for a few months. Then people will start discovering them and gradually their server will get more and more overloaded, eventually they'll reach their prepaid bandwidth quota and they'll start having to pay more for bandwidth. Your website will gradually slow to a crawl and your customers will get impatient and go elsewhere. If the host is sensible they'll either impose a fair usage policy, or start putting real limits on bandwidth. If they're not, their servers may just continue to get bogged down until they're completely unusable. Again, this will mean your website is either un-usably slow or down completely, losing you customers and money.
True unlimited bandwidth is a massive drain on the web host providing it and the web host will eventually buckle under the pressure.
Other unlimited bandwidth providers try to limit the amount of bandwidth you use by restricting what files you upload, many blocking audio or video files. While this serves to reduce the total amount of bandwidth that your website uses quite substantially, it does nothing to reduce the load your website puts on their server (video and audio downloads don't tend to put a great deal of load onto the server). This means these web hosts would still be required to upgrade their hardware regularly and may be subject to slowdown. You may find that some content limited hosts would are quite speedy, and if you're willing to trade bandwidth for content freedom, one of these hosts may be suitable for your website.
The author (Kieran Simkin) is an experienced web developer and co-founder of a successful web hosting business.