05-08-2009 06:24 AM - edited 03-06-2019 05:37 AM
Doing some testing, a question came up asking me to consider each multiple choice and decide which one(s) will have the end result of PC2 and PC3 being in SW2's MAC address table.
The diagram which also includes the exhibit (show's output) are found here (public URL/no login):
http://www.facebook.com/photo.php?pid=2652380&l=d56dea0cf3&id=502714417
I understand both B and D are correct answers, but I also thought that C would be a correct answer.
Thanks
05-08-2009 06:29 AM
Erik
C is not a correct answer because a switch learns which mac-address is tied to which port based on the source mac-address in the frame. So in C all SW2 would learn is that R1's mac-address is on fa0/4.
Jon
05-08-2009 06:43 AM
But since the router communicates with those two PCs, wouldn't it have to at some point send an ARP broadcast using their IP to find out their MAC address before it can deliver an ethernet frame to each of those hosts?
05-08-2009 06:50 AM
Erik
I don't disagree with what you are saying but whereas 2 & 4 will result in SW2 learning the mac-addresses of PC2 & PC3 answer 3 does not result in this, rather you have to assume that something else has happened first.
What if for example you entered static entries in the arp table on R1 ?
Jon
05-08-2009 07:07 AM
I see now, I wasn't paying enough attention on the keywords. I said it myself, the question is "which situation WILL RESULT" and perhaps those were the two key words.
Thanks,
Erik
05-08-2009 07:17 AM
Erik
No problem. A lot of Cisco questions are like this, a bit ambiguous.
Jon
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