which option is better for hyperlink path?

Question

hello which option is better to use in hyperlink's NavigateUrl property..

to write like NavigateUrl="default.aspx" , NavigateUrl ="cart.aspx" n so on...

or i should like the path wich displays in the web browser like:

NavigateUrl ="http://localhost:2918/AJAXEnabledWebSite2/default.aspx"
NavigateUrl ="http://localhost:2918/AJAXEnabledWebSite2/cart.aspx"