Question : Problem: How do you know if a wireless network is 2.4ghz or 5ghz?

Im getting an asus netbook that only connects to 2.4ghz. I have cable that connects to an apple router.
thank you

Answer : Problem: How do you know if a wireless network is 2.4ghz or 5ghz?

I just realized you said Apple router, the Airport and the Airport extreme are either 802.11b or 802.11g respectively, both are 2.4ghz routers.  The cable doesn't matter.