Mac OSX is based on BSD Unix, so that covers the Linux angle. I know several Unix/Linux sysadmins who like using a Mac. Mac/Windows doesn't matter for Cisco. If he gets farther along in his Cisco studies and starts using emulators instead of shelling out $$$$ for routers, he will be able to run dynamips on the Mac.
Cisco network administration is my day job, so if you or he has any questions, feel free to ask.
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"The shortest distance between two points is usually under repair." - Anonymous
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