[dns-operations] question for geo-based response

[Lauren C.]

Greeting,

Sorry I am a web developer, know few about DNS knowledge.

When I dig www.fb.com from within the server which is located in the US:

$ dig www.fb.com @8.8.8.8 +short
www.facebook.com.
star-z-mini.c10r.facebook.com.
157.240.22.39

Then I dig the same domain from within the server which is located in HK:

$ dig www.fb.com @8.8.8.8 +short
www.facebook.com.
star-z-mini.c10r.facebook.com.
31.13.95.38

The IP addresses I got in the response are totally different.

How open resolver returns different results for the same query against 
different client location?

thanks.