Most reasonably technical Internet users have a pretty good idea what DNS is, but what actually happens when you look up a domain name is not always so clear. For those of you who are a bit uncertain of how it works (or just like geeky server charts), we found an excellent picture describing the chain of events of a DNS lookup.

The image below is from Verisign, and to simplify matters a bit it ignores the effect of caching (normally results are cached at various points along the chain):

Image source: Verisign Domain Name Industry Brief, June 2007 (PDF), last page.

The chain of events to get the IP address for www.abc.com:

First your computer queries the name server (DNS server) it is set up to use. This is the recursive name server shown above.

The name server doesn’t know the IP address for www.abc.com, so it will start the following chain of queries before it can report back the IP address to your computer (the numbers below correspond to the numbers in the image).

1. Query the Internet root servers to get the name servers for the .com TLD.
2. Query the .com TLD name servers to get the authoritative name servers for abc.com.
3. Query the authoritative name servers for abc.com to finally get the IP address for the host www.abc.com, then return that IP address to your computer.
4. Done! Now that your computer has the IP address for www.abc.com, it can access that host.

This won’t be news to some of you, but you have to admit it’s a good picture! Definitely worth sharing.

Trailblazers, creatives and innovators have taken the Internet to where it is today and made it an essential part of our everyday lives. We have selected a number of interesting “firsts” from the history of the Internet (and the Web) for your reading pleasure.

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Facebook has announced that it now has 400 million active users. Just one year ago Facebook had 150 million users, so 2009 was an incredible year for the social media giant.

There can be no doubt that Facebook is pretty much unstoppable at the moment, a real juggernaut. For some perspective on Facebook’s amazing growth, we have put together this infographic. We hope you’ll enjoy it!

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Sometimes you want an easy way to share your Pingdom monitoring data with others. So far we’ve had public report pages that you can use, but now we’ve added one more sharing method that is very flexible and easy to use.

Enter our new “report banners”.

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Unless you’ve been hiding under a rock lately, you’ll know that last week Apple announced the iPad, its new tablet device. Reactions have been a mixed bag, and a storm of discussion has swept through the blogosphere about various features the iPad should or shouldn’t have had.

One of the main complaints so far has been the iPad’s lack of multitasking. (To be precise, multitasking is a bit of a misnomer here; the iPhone OS has multitasking. What people really mean is only allowing one app at a time to run.)

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The tech industry is littered with billionaires. We all enjoy a good income, but some clearly have earned more than others. Much, much more. The question is, how much money do the really big names in tech actually have?

To find out, we went through the Forbes 400, a list of the wealthiest Americans, and filtered out the people who work within the tech field, or more specifically: IT.

So here they are, the 20 richest Americans in tech today.

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