MCSE : Security
19. Repeaters, Bridges, and Routers:
I. Repeaters work at Physical layer (Layer 1),
II. Bridges
and simple switches work at Data Link Layer (Layer 2),
III. Routers
work at Network Layer (Layer 3) of ISO Reference Model.
20. CSU / DSU is an acronym for Channel Service
Unit / Data Service Unit. CSU/DSU is part of Customer Premise
Equipment (CPE). CSU / DSU connect to a Central Office (CO), a
telephone switching company located nearer to the customer.
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