I’m presently using an internet terminal in the Amsterdam airport, because I accidentally left my Blackberry in Houston.  Off to Dublin in a couple of hours, and I’ll be back home next week.  I’m sure I’ll have something interesting about which I can blog by then.

Happy St. Patrick’s Day!

1: The “F” in WiFi does not mean “Free”.

If I had a nickel for every time someone insisted that “WiFi” means “Wireles Internet, Free internet,” I’d need help lifting my huge bag of nickels.

“WiFi” is a play on the term “HiFi,” which means “High Fidelity” and applies to audio recording technology.  While some free public WiFi networks do exist, there are a large number of paid services available in coffee shops, airports, hotels and other places.

You have to pay for internet at home — is it really so unbelievable that you’d have to pay for it elsewhere?

2: The maximum reach of 802.11g WiFi is 300 feet.

That’s 300 feet outdoors, with no interference.  For indoor access points, the recognized average is 120 feet.  If you live next door to a coffee shop that provides WiFi, chances are that there’s too much steel, wood, concrete, insulation and drywall between you and the wireless router for you to get a reliable signal.

Furthermore, the wireless antenna built into your laptop is not very powerful.  You can use a utility like Netstumbler to survey the wireless networks available to you, and assess what signal strength and quality you can expect to receive from them.

Generally speaking, if you’re looking to receive WiFi in your home, you’re going to have to get a cable or DSL connection and set up a wireless router.  With the exception of a few cities that provide municipal WiFi networks, WiFi is not something that you can receive in your home from an outside source; and the municipal networks can be sketchy — I don’t recommend them.

3: Almost everything interferes with WiFi.

WiFi operates at 2.4 GHz — just like most cordless phones, Bluetooth, some RF signals, and a host of other electronic communications devices.

WiFi will go through one or two walls without much degradation, but it can be interrupted by microwaves, CRT televisions, reflective surfaces, other computers using WiFi, other WiFi signals broadcast on the same channel… the list goes on.

This shouldn’t dissuade you from using WiFi altogether!  If you have a wireless router in your house, you’ll probably get great reception from it — WiFi is primarily intended for short-range, single-building connectivity.  It is possible to stretch it farther with high-gain equipment, but that can become costly (and if you’re going to shell out the money, why not get a cable or DSL connection instead?).

4: Business Class service for your business.

There is a reason that businesses pay extra for business class service.  Business class connections come with things like guaranteed uptime and redundant circuits — ISPs prioritize outages for business class customers, and have extra measures in place to meet their needs.

Basically, you may be able to run your business on residential service or public WiFi if you require intermittent connectivity to the internet; but if the possibility of 3-5 days’ downtime would cripple your business or shut you down completely, you need business class.

5: Free WiFi in apartment complexes is worth every penny.

If you’re moving into a new apartment and the offer Free WiFi, be suspicious.  Depending on which apartment you get, the signal may not reach into your unit very well.  You may have to sit on your patio to get online.  For the amount that they add to your rent, you could probably get a DSL connection of your own.

Furthermore, even if you get a good signal and the hotspot equipment is working fine, the bandwidth available to the service is split between everybody who’s using it; and if one of your fellow tenants is downloading torrents with wild abandon, it can severely slow down your connection — or worse, the management might have opted for a low-bandwidth plan, or may be blocking some ports or services.

If you’re considering an apartment with free WiFi, at least ask questions:

• How much total bandwidth is available?
• Is there a cap on my bandwidth or usage?
• Are any sites/ports/services blocked?
• Who provides the service, and do they offer competent technical support?
• Can I opt out?

Whether you can opt out or not, you should still be able to get your own DSL or cable connection.  Make sure you know all of your options.

6: All connections are NOT created equal.

While a WiFi connection may be suitable for checking your email or looking up movie times, if you’re trying to stream HD video, be prepared for disappointment.  No WiFi provider is going to guarantee any minimum level of bandwidth or speed.

Of course, this doesn’t necessarily apply to the wireless router in your house running on your cable or DSL connection; this unobstructed, unshared signal can be just as reliable as plugging a cable directly from the modem into your computer.

7: Bandwidth vs. WiFi transfer rate

802.11g has a maximum transfer rate of 54 Mb per second.  That’s megabits, not megabytes — there are 8 bits in a byte, so wireless-G is capable of transferring up to 7 MB per second.  The newest standard, 802.11n, doubles that: 108Mb/14MB per second, under optimal conditions.

This does NOT mean that you’ll be able to download at this rate.  A standard DSL connection will run anywhere from 3-7 Mbps, so you can download from a website at almost 1MB per second (optimally).  Cable connections typically run from 5-15 Mbps, so you may be able to get close to 2MB per second from the web — assuming, of course, that the web server from which you’re downloading makes that speed available to you.

In short, a 54 Mbps WiFi connection should not lead you to believe that you can download a 1-gigabyte file in under a minute.  Remember:

1. Know the difference between bits and bytes
2. Your router’s transfer rate is limited by your connection’s bandwidth
3. Your download rate may be capped by the server providing the files

Public WiFi is great for checking your email or looking up web pages, but it’s not reliable as a constant connection.  The best description of the service you’ll get?  Results May Vary.

To understand how DNS works, you need to know one simple concept: humans like words, computers like numbers.  For example, if you type either of the following into the address bar of your web browser, you’ll get to the same place:

• 208.17.81.60
• www.salon.com

208.17.81.60 is the IP address for the online news site Salon.com.  When you type www.salon.com into your browser, the browser queries a DNS server (“do you know where this is?”).  The DNS server will either tell the browser where it is, or forward the request to another DNS server (“I dunno, go ask that guy”).  Within a few hops, your web browser will learn that “www.salon.com” means “208.17.81.60″, and bring up the page for you.

This is how sites “spider” onto the internet.  If your primary DNS server doesn’t know a particular address, it sends the request along to other DNS servers; in most cases, when the query is finally answered by a DNS server that knows what you’re looking for , the servers that sent the request along will overhear the response that your browser receives, and record the record in its own database.  This way, if anyone else asks for it, the server will be able to offer up the information without having to pass the request along.

If DNS servers didn’t operate this way, it could take a very long time for you to reach ANY websites.  Imagine what would happen if only one DNS server in the world knew how to get to Google!  You’d have to stand in a very long line to check your Gmail.

If you have a home internet connection, your ISP is providing you with a DNS server or two (or three).  Some companies provide public DNS servers — Google, for example, provides 8.8.4.4 and 8.8.8.8.  If you mysteriously find yourself able to get to some websites but not others, and you know where in your network your DHCP servers are set (usually in your router), you can try replacing your primary DNS server with a public DNS server to see if it fixes the issue.

For quick and easy DNS tests, you can go to DNSsy.com.