Challenge Questions Challenging questions hand picked from Certification Zone's exstensive and esteemed Practice Exam database
CCNP™Challenge Question
Which of the following protocols is a specification for the interconnection between DTE and DCE at the data link layer?
a)
SDLC
b)
X.25
c)
HDLC
d)
Frame Relay
Answer
d)
Frame Relay
Explanation
Cisco may simplify some definitions, and you need to know what they are looking for on the certification exam. Unfortunately, not all Cisco documents are consistent in explaining DTE-DCE relationships. The focus here is on layer 2 interactions, although there can be DTE-DCE interactions at multiple layers.
One good training slide I've seen describes three sorts of relationships:
End host to router (e.g., SDLC- or BSC-attached legacy device)
Router-to-router (e.g., HDLC, PPP, or LAP-B)
Router to service provider (e.g., Frame Relay, X.25/LAP-B, ISDN)
Strictly speaking, the DCE comes from a service provider, and the DTE is from the user side. When answering any Cisco question, look for what appears to be the user side versus the provider side.
ISDN and Frame both share the property of being local access protocols to a provider. Indeed, there are Frame over ISDN services. X.25 is also a local access protocol that runs over a data link layer of LAP-B.
Certification Zone is an independent product, not sponsored by, endorsed by, or affiliated with Cisco Systems, Microsoft Corporation, or the Field Certified Professionals Association. Cisco®, Cisco Systems®, CCNA™, CCNP™, CCVP™, CCIE™, CCSI™, and the Cisco Systems logo are trademarks or registered trademarks of Cisco Systems Inc. Microsoft®, Windows®, Windows 2000™, Windows 2003™, MCSA™, and MCSE™ are trademarks or registered trademarks of Microsoft Corporation. FCSA™ and FCSE™ are registered trademarks of the Field Certified Professionals Association.
