Your ISP's DNS server returns IP addresses even for domain names which should not resolve. Instead of an error, the DNS server returns an address of 52.74.158.221, which resolves to ec2-52-74-158-221.ap-southeast-1.compute.amazonaws.com. You can inspect the resulting HTML content here. 

There are several possible explanations for this behavior. The most likely cause is that the ISP is attempting to profit from customer's typos by presenting advertisements in response to bad requests, but it could also be due to an error or misconfiguration in the DNS server.

The big problem with this behavior is that it can potentially break any network application which relies on DNS properly returning an error when a name does not exist.

The following lists your DNS server's behavior in more detail.
•www.{random}.com is mapped to 52.74.158.221. 
•www.{random}.org is mapped to 52.74.158.221. 
•fubar.{random}.com is mapped to 52.74.158.221. 
•www.yahoo.cmo [sic] is mapped to 52.74.158.221. 
•nxdomain.{random}.netalyzr.icsi.berkeley.edu is mapped to 52.74.158.221. 

Your host, NAT, or firewall acts as a DNS server or proxy. Requests sent to this server are eventually processed by this number. I have not given the number It is in my router as alt dns server. It seems that the ISP does not know much about these things while configuring the first time

This is probably a bug in your NAT's firmware, and represents a minor security vulnerability.