Why is the data-link layer most diverse?

I'm doing a Cisco's Networking Devices (ICND1) Review Questions - Module 1

Which area of the OSI model and the TCP/IP stack is most diverse?

network layer
transport layer
application layer
data-link layer

So why data-link layer? Transport layer has all the ports...

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instant000

I would put them in this order (most diverse to least diverse):

application [tons of apps out there]
data-link [ many, many layer 2 protocols]
network [more network protocols than transport protocols]
transport

This is really one of those questions that you hope you don't get on the test. As you can see, my list is different from yours. I'm not sure what they mean by diverse. Do they mean the most diverse protocols? There are more application protocols than data-link layer.

I feel that question is incomplete, or I'm just not looking at it correctly.

pamccabe

I would agree with instant's list. The only thing I can think of is that the CCENT focuses more on layers 1 - 4. In that regard, maybe layer 2 is more 'diverse'. Hard to say without knowing what diverse means in this situation.

instant000

I researched this particular question, and this is what I have come up with: it's just a bad question.

This person posted this list, (June 2009) and it says that "application layer" is the correct answer to the question.
Answers for Interconnecting Cisco Networking Devices (ICND) Practice Questions- Module 1 – with explanations | IT Certifications

This website says the data link layer is most diverse (though it does not qualify the statement). (February 2012)
Cisco ICND1 Flashcard: OSI Layer Model and PDU's | Cisco Exam Study Notes

Someone asked this same question on techexams in the past. It was agreed then (200

that it was a poorly-worded question.
http://www.techexams.net/forums/ccna-ccent/27791-icnd1-question.html

You post your question in 2013, so I guess the bad question has not been updated.

The very fact that you question their logic (since they do not say in what way they want it to be diverse) means that you're going beyond just accepting questions and answers at face value. You should do just fine, if you maintain this attitude for everything that is provided.

When in doubt, lab it up and ask questions.

Hope this helps!

CCNTrainee

Taking a guess, would the fact that Data Link protocals differ when it comes to WAN technology play a part?? Since they don't use MAC address and Frame-Relay, ATM, HDLC, etc take its place on Layer 2??

I do get and agree that the App layer has a LOT of options.

binaryhat

Thanks for the in depth responses:D. The ? bothered me. Looks like Cisco needs to update it's practice ? material.