Hi,
        How to track sub-domains links?

Regards,
jeya vinoth

Cross-domain tracking is a term we use to describe the act of tracking multiple domains in a single Google Analytics property. ... The truth is that most Google Analytics users are tracking just one domain name at a time

Hi Friends,
Subdomains are tracked but there is a filter that you need to have Google Analytics display it (instead of /whatever as it is in default configuration).

• Filter Type: Custom filter > Advanced
• 
  Field A: Hostname Extract A: (.*)
• 
  Field B: Request URI Extract: (.*)
• 
  Output To: Request URI Constructor: $A1$B1