[nmridul]

The poster you are replying to could possibly be Indian. Possibly this could be one reason (Disclaimer - I am just assuming and not answering for him)

In India last name could mean anything ranging your "caste" / religion / community / god / place / family / fathers name / or any other random stuff.

Singh is a common last name and if you go to some parts and call Mr. Singh and possibly 100's would respond. And there are people with surname "Bangalore" because they were born there.

And in my part of South India, some of our last name is "First name" of our parents (mostly Father.. nowadays people also started adding their mother's first name). So my name is "My first name" + "My father's first name. And my son is named "Son's first name" + "My First name". It continues this way.

So most of us use the First name to mention someone. And you can see many Indian's making the mistake of addressing some one as "Mr. First name" though the proper usage is "Mr. Last name".

I had this difficulty when in Germany a government office asked why I have a different surname from my kid's and I had a hard time explaining it :)