page.. I find that on the server side the HTTP_HOST instead

In my browser(Maxthon) When I give refresh to an URL name:
m.example.com/page..

I find that on the server side the HTTP_HOST instead gets:
www.example.com/page..

This is very strange. What could be the reason of it? It is happenning sometimes even with other browsers as well.

From the Network tab of the browser I've grabbed this Request/Response Headers:

Request URL:http://m.governmentjobsindia.org/30-deputy-manager-posts-national-highways-authority-delhi
Request Method:GET
Status Code:200 OK
**Request Header** sview source
Accept:text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Referer:http://m.governmentjobsindia.org/30-deputy-manager-posts-national-highways-authority-delhi
User-Agent:Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/535.12 (KHTML, like Gecko) Maxthon/3.0 Chrome/18.0.966.0 Safari/535.12
**Response Headers** view source
Cache-Control:public, max-age=900
Content-Encoding:gzip
Content-Language:en
Content-Length:12696
Content-Type:text/html; charset=utf-8
Date:Wed, 18 Mar 2015 10:55:05 GMT
Etag:"1426675521-0"
Expires:Sun, 19 Nov 1978 05:00:00 GMT
Last-Modified:Wed, 18 Mar 2015 10:45:21 +0000
Link:<http://www.governmentjobsindia.org/30-deputy-manager-posts-national-highways-authority-delhi>; rel="canonical",<http://www.governmentjobsindia.org/node/4675>; rel="shortlink"
Server:Apache
Vary:Accept-Encoding
X-Drupal-Cache:HIT
X-Generator:Drupal 7 (http://drupal.org)
X-Powered-By:PHP/5.3.10-1ubuntu3.13