Interesting article written last week at Royal Pingdom — Google availability differs greatly between countries, where Pingdom, a server/web-site availability monitoring company based in Sweden, tried to measure the uptime of Google’s country-specific websites. The conclusion is —

Google Search users in the United States are 10 times more likely to encounter a problem than users in Brazil, according to this unique one-year survey from Pingdom.

When it comes down to analysing the result,

It is interesting that several countries not traditionally associated with a good internet infrastructure ended up in top positions with very little downtime. Notable examples are Brazil, India, Thailand and Mexico.

Sweden on the other hand has a reputation for being one of the forerunners on the internet, so it is very surprising to find the Swedish Google Search at the bottom of the list.

The story was submitted to Digg, and then got published on TechCrunch where a bit of discussion was generated. So, does that proves Brazilian’s technology superiority?

What I couldn’t get my head around Pingdom’s test is, how can they measure and compare the uptime of individual country-specific Google sites, when every country-specific Google site except one is CNAME’ed to www.l.google.com?

$ host www.google.com.br
www.google.com.br is an alias for www.google.com.
www.google.com is an alias for www.l.google.com.
www.l.google.com has address 74.125.19.103
www.l.google.com has address 74.125.19.104
www.l.google.com has address 74.125.19.147
www.l.google.com has address 74.125.19.99
$ host www.google.com.au
www.google.com.au is an alias for www.google.com.
www.google.com is an alias for www.l.google.com.
www.l.google.com has address 74.125.19.103
www.l.google.com has address 74.125.19.104
www.l.google.com has address 74.125.19.147
www.l.google.com has address 74.125.19.99
$ host www.google.com.tw
www.google.com.tw is an alias for www.google.com.
www.google.com is an alias for www.l.google.com.
www.l.google.com has address 74.125.19.103
www.l.google.com has address 74.125.19.104
www.l.google.com has address 74.125.19.147
www.l.google.com has address 74.125.19.99

Basically, it does not matter whether you are querying the Brazilian Google, the Aussie Google or the Taiwanese Google, it is all going to the same set of load balancers. Therefore saying “Google Brazil has better uptime” actually does not make any sense, because quite possibly the same servers powering Google Brazil is also powering Google US and Google Sweden. They might be sending to a different backend behind the load balancer, but the differences between uptime would have nothing to do with how advanced that country is in terms of Internet technology (which Pingdom was trying to correlate with the site’s uptime).

The only exception is www.google.com.cn:

$ host www.google.com.cn
www.google.com.cn is an alias for cn.l.google.com.
cn.l.google.com has address 72.14.203.160

I guess Google China has some “special features” to prevent innocent Chinese citizens from discovering indecent information online. However the address still resolves to Google’s facility.

Another thing to note is, the IP address of www.l.google.com actually differs depending on where you make the query from. For example from Australia and from US east coast, it always resolves to 74.125.19.x. From my VPS at Slicehost which is in St. Louis MO, www.l.google.com resolves to be 64.233.169.x, which I suspect is in Atlanta GA. From a UK resolver it also gives me back a Google IP address that routes to London. I do not have access to resolvers elsewhere but I suspect Google will return IP addresses of the nearest data centre in the world.

Therefore, while Pingdom might be checking the availability of www.google.co.uk from various locations in the world, the monitor nodes could be testing against different servers in different data centres, all responding to the same URL! So, is Google up? That depends…