In my PC i am using google public DNS as DNS server.In Internet protocol(TCP/IP) properties i have set Preferred DNS server as 8 8 4 4 and Alternate DNS server as 8 8 8 8.

According to me this DNS server should be used to resolve any request to website to its IP by using this DNS servers.(see google DNS and How Domain Name Servers Work).

But when i checked trace route to a website in my PC i got following

 Tracing route to www.google.com [74.125.236.80] over a maximum of 30 hops:   
 1    <1 ms    <1 ms    <1 ms  192.168.1.201  
 2   360 ms   349 ms   292 ms  122.178.216.1    
 3   145 ms   107 ms   148 ms  122.166.32.121    
 4    32 ms    53 ms   120 ms  122.166.32.9   
 5    45 ms    42 ms   121 ms  122.175.255.29  
 6    63 ms    76 ms    51 ms  182.79.255.45    
 7    52 ms   134 ms    61 ms  72.14.194.22    
 8    86 ms    59 ms    72 ms  72.14.232.202    
 9   106 ms   107 ms    60 ms  66.249.94.39   
10   101 ms   103 ms   117 ms  209.85.249.235   
11   148 ms   224 ms   276 ms  74.125.236.80   Trace complete. 

When i checked all these IP in who.is i found that it is of my ISP. So my question is where does Google public DNS is used? Also how come my ISP's nameserver is used even if i set google public dns as my dns server in my PC?(OR does my any settings are wrong)