There have been lot of news about Airtel blocking blogspot today.

  • Make Telecom Talk My Trusted Source
  • Source of Google
  • Source of Google

Well, did they really blocked it?

It’s very hard to give a direct answer to that. Firstly, I believe that Airtel must have not intentionally blocked whole blogspot.com domain name (well they are a big ISP, and I don’t think they will go that kidish!).

What could be problem?
To understand that – let’s break Internet connection into parts as per TCP/IP model

1. Physical layer + Data Link layer on bottom most

2. Network layer – DNS, Internet routing, BGP stuff

3. Transport + Application layer – web browsers, scripting, web servers, data rendering etc

Well – Physical and data link layer were not really issues – since people who were having issues must be on a system “connected” to Internet, and same with Google’s Indian mirrors (which are usually on datacenter with redundant physical links)

Next, we see #2 Network layer – yes there can be issues here. And since people were not able to open website at all, rather then getting error 404, 500 or say a broken site – there was not really issue with Transport + Application layer.

So what can be possible issues at Network layer?

Broadly speaking – it consists of two parts – DNS and Internet routing.

DNS, as I explain is last post simple resolves www.blogspot.com into IP address. I have seen a few traceroutes on Internet – and they are all timing out after a certain IP address. From that it clearly seems issue was not on Airtel’s DNS servers. If it was issue at DNS servers – then would be getting – “Name not found” error in web browser, rather then “request timed out”.