Quick question... which layer defines end-to-end delivery...

AnthonyJD81

I have noticed several differences in a couple practice exams and study guides. The one that mainly confused me is this:

HERE ...OSI exam#2(question#14) asks
"Which layer defines end-to-end delivery of packets?"
a . Physical
b . Transport
c . Network
d . Data Link

Now I would say its the Transport layer because that layer handles flow control...basically disassembly and assembly of data.
My Cramsession study guide I bought and printed out says that the Transport layer handles "end-to-end connectivity"...is there a difference in the wording of the two between connectivity and delivery or is it infact the Transport layer and NOT the Network layer?

Oh btw, the answer to this question according to the site was C (Network layer)...which i disagree with.

Correct me if i am wrong or shed some light on this please...thanks!

Webmaster

This is a confusing one indeed and I also noticed a lot of contradictions on the web, but I think I can explain this easily:

The Network layer is responsible for end-to-end (also named source-to-destination) delivery of individual packets across multiple networks, without guarantees. The network layer treats these packets independently, without recognizing any relationship between those packets.

The Transport layer is responsible for end-to-end delivery of entire message.
Provides end-to-end connectivity, It allows data to be transferred reliably (for example, with a guarantee that it will be delivered in the same order that it was sent)