i saw this link somewhere else, maybe in the cisco forums:
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i've been using them for practice CIT tests , really helpful, but they have most of the cisco practice exams. there is also a link to a free lab
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but it is all booked thru september. the free lab pods have several routers but only one switch, so it would mostly be helpful for routing (and Frame/Relay).
no ads or pop-ups. completely legit site.
-ccna,ccda,ccsp