Quiz 4, 2018, Q2

Quiz 4, 2018, Q2

by Christoph Andreas Ungricht -
Number of replies: 3

Hi, it's me again :)

I was wondering why exactly in Quiz 4 of 2018 the answer to question 4 is D: "It  occurs  when  routers  have  multiple  next  hops  to  the  same  destination;  routers identify which packets belong to the same flow by looking at source and destination MAC addresses and send packets of the same flow to the same next hop."

In this case answer A "It occurs when routers have multiple next hops to the same destination; routers identify which packets belong to the same TCP connection by looking at source and destination IP addresses and port numbers and send packets of the same TCP connection to the same next hop" is only wrong because of the statement concerning the TCP connection? If only source/destination IP and/or port number would have been stated answer A would also be correct?

Thanks for clarification!

Chris

In reply to Christoph Andreas Ungricht

Re: Quiz 4, 2018, Q2

by Ludovic Thomas -

Hi Chris,

Answer D cannot be true because ECMP cannot be based on MAC adresses (layer 2). 

So I would say that the most probable situation is that the intended answer was A as you propose (highlighting is probably incorrect). However, it's true that ECMP does not only happen with TCP flows, however we might consider A correct because it's not written explicitly "only with TCP flows".

Anyway, as I'm not entirely sure, we'll have a better answer by tomorrow morning. 

Cheers!

In reply to Ludovic Thomas

Re: Quiz 4, 2018, Q2

by Ludovic Thomas -

Hi,

just got confirmation:

correct answer of Quizz 4 - 2018 - Question 2 should be A.

Thanks for reporting,
Ludovic