It's a bit of a crapshoot when one connection goes down, but here's a short explanation.
As you probably already know, our server is hosted behind two DSL (Digital Subscriber Line) connections, which provide Internet access for Army.ca. Each DSL connection has a unique IP (Internet Protocol) address, but normally you don't know or care. All you do is plug army.ca into your browser, and it "magically" knows how to get here. To do that, your computer asks DNS (Domain Name Services) to give the IP address for Army.ca. If there was just one DSL connection, army.ca would always resolve to the same address. When that one connection goes down, obviously the site would be completely inaccessible.
However we have two DSL connections and two IP addresses, which changes things up a bit. Now when you look up one of our many hostnames (E.G. www.army.ca, forums.navy.ca, milnet.ca, etc.) it returns the IP addresses to both connections, in random order. In a command prompt you can type
nslookup army.ca to see this in action. That'll return these two addresses:
- 216.58.85.243
- 216.58.41.151
These are, as you probably guessed, the two actual addresses of our DSL connections, and ultimately the final destination for all requests to the site. You can even visit these directly by plugging the IP addresses into your browser (http://216.58.85.243 and http://216.58.41.151) but trust me, they won't look as "pretty" as using one of our hostnames, and they're a heck of a lot harder to remember. (Anyone out there still remember when we were located at cpu2212.adsl.bellglobal.com? That was a low quality hostname if ever there was...)
Most applications like Firefox/IE will take the first IP address returned and try to connect to that. That means that by retuning the two addresses in random order, we instantly have load balancing. Half of your will come here on DSL connection 1, the other half on DSL connection 2. Moreover, as your DNS cache expires, and your computer "forgets" that army.ca is at 216.58.41.151, you'll look it up again, and may come back in over the other connection. This automatically keeps things balanced and running smoothly. At least when things are already running smoothly.
If one connection goes down, there's a 50/50 chance it's the one you're trying to use. If that happens, your browser will [normally] try the second DSL connection automatically, but it takes a loooong time to decide that the first address well and truly isn't responding. In the mean time, you wait. What's worse, even if army.ca resolves to an address that works for you, the page you're reading may have images linked from forums.army.ca, which may resolve to the IP address that's down. When that happens, the page will still load slowly, often in fits and starts.
The good news is, as uncle-midget alluded to, that you might be able to beat the system with a bit of perseverance. If www.army.ca doesn't work, trying other sites like forums.army.ca means you take another shot at resolving the hostname, and maybe this time you get the DSL connection that's still up returned as the first address. If you're stuck using the connection that's dead, you can also force your computer to forget that address and try again (see above re: DNS cache). Simply enter
ipconfig /flushdns at a command prompt. Note that you'll likely need to close your browser, issue the command, and re-open it for things to work completely... your browser remembers stuff too.
Not for the faint of heart, but there's also another (better) way to cure your Army.ca DTs that involves tricking your system into thinking that there's only one connection to army.ca - the one that's up. I'll post that another time.
Hopefully this explanation is helpful to some. If you've read this far through such a dry and insignificant post, you've officially earned the title "Army.ca Addict" - congratulations!