Refer to the exhibit. After HostA pings HostB, which entry will be in the ARP cache of HostA to support this transmission?
A. 
B. 
C. 
D. 
E. 
F. 
After HostA pings HostB, which entry will be in the ARP cache of HostA to support this transmission?
Refer to the exhibit. After HostA pings HostB, which entry will be in the ARP cache of HostA to support this transmission?
When a host needs to reach a device on another subnet, the ARP cache entry will be that of the Ethernet address of the local router (default gateway) for the physical MAC address. The destination IP address will not change, and will be that of the remote host (HostB).
no.answer a
see this!!!
http://www.cisco.com/en/US/tech/tk648/tk361/technologies_tech_note09186a0080094adb.shtml
The answer is option – D.
In this case, the arp entry on host A would hold the mac of router interface and the IP address of default gateway (which is the same router interface). I have checked and verified this topology in Packet Tracer as well as in real network.
Well, as per theory this is not right but in real world, it is… Mysterious !!
that’s true!
arp cache can only see local subnet, not the other subnet. it’s different from the frame that contains the destination ip add and default gateway’s ip address.
correction, default gateways’s physical address
@Majid
It is of course right in theory too.
What host A would do is:
– Host A knew that the IP address of host B is not in the same subnet so it would send the ICMP message (or ping) to default gateway which is 192.168.6.1 (fa0/0). However, it needs to know the actually physical address of this IP address to do so.
– To get the MAC address host A will send ARP request (broadcast) with the IP address 192.168.6.1 as destination. F0/0 gets it and send back the MAC address. THIS MAC ADDRESS and the IP address 192.168.6.1 of F0/0 will be recorded in ARP cache of host A for future use.
I think you guys mistaken this ARP cache with the actual ICMP message which have IP header with IP address of host B as destination. The ARP cache only supports host A to get MAC address of Fa0/0 (default gateway), it has nothing to do with the ping message host A sends to host B.
Wrong table’s heads. In ARP cache result we can see “internet address”, not “interface address”
Answer is wrong. See:
http://www.cisco.com/en/US/tech/tk648/tk361/technologies_tech_note09186a0080094adb.shtml
and note that ARP cache reflects IP of Host B and MAC of router1 interface fa0/0
so.. what is the Answer?
I think.. maybe.. The answer is A.
It depends what is the subnet mask of HostA and whether it deffers from the subnet mask of hostB.
@CiscoStudent The link with Proxy ARP you provided is a different case, in it hostA have /16 mask and it thinks that hostB is in the same subnet, but in the question both hosts have /24 mask , so hostA would know that hostB is not in the same subnet and will send packets to Default GW.
So I think correct answer is D.
this questions is confusing. but host A will send an ARP to all interface on the same subnet and the local interface too, when it get the response from the gateway its will use the forward trafic to Host B. Remember during encapsulation only the mac address will change the ip address of the destination will remain same. in my opinion i think A is correct. because host A use the mac address of local router interface and the ip address of the destination host B
I am completely agree with you #sniffer
Yeah, but in this case hostA knows that hostB is in different subnet, therefore will try to reach it via the Default GW, but as it knows only the ip address of the GW from its configuration, hostA will send ARP request for determing GW mac based, therefore it will have mac and ip addresses of the GW, not of hostB.
I think the corect answer is D not A.
The host send packet to gateway to send packet to host B
guys just think of when host use the destination ip of 192.168.6.1 router will think that the request if for him. and he will never forward that message to host b. because he think that message is for him. got it?
thats why we use 2 addresses for routing.
while sending data to hostB, hostA would send the destination IP as the B’s IP only, but for making this decision, A’s MAC table should have a default gateway and this should have the details of routers interface connecting the A’s LAN. hence the answer is “B”, cause this entry in the MAC table will help host-A make this decision.
Correction- by mistake i said “the answer is “B”. actually it’s “D”. with the logic/explaination given below.
while sending data to hostB, hostA would send the destination IP as the B’s IP only, but for making this decision, A’s MAC table should have a default gateway and this should have the details of routers interface connecting the A’s LAN. hence the answer is “D”, cause this entry in the MAC table will help host-A make this decision.
http://www.cisco.com/en/US/tech/tk648/tk361/technologies_tech_note09186a0080094adb.shtml
here is the correct answer.i agree with CiscoStudent
@tani10
That link is for Proxy ARP, this setup doesn’t mention Proxy ARP being utilised, and the subnet on HostA doesnt cover HostB so Proxy ARP is not being used!
The Answer is D.
If in doubt run a on your PC do a ‘arp -a’ to list all the arp entries, then ping a remote IP address and run ‘arp -a’ again. Your arp cache will have an entry for your default gateway IP & MAC, but will not have an entry for the remote IP.
Answer is D.
D is the Correct Answer.
I Test This Using Packet Tracer , After Pinging Host B Only 192.168.6.1 address in the ARP Table, No Entry for Host B
It’s the besst time too make a few plans for the
long run and it’s time to be happy. I’ve read this pot and if I maay just I wish to recommend you few attention-grabbing things
or suggestions. Perhaps youu can wrte subsequent articles regarding this article.
I desire to read even more things about it!
I simply couldn’t go away your site prior
to suggesting that I extremely enjoyed the standard info a person provide for
your guests? Is gonna be again incessantly in order to inspect new posts
What’s up to all, how is everything, I think every one is getting more from this website,
and your views are good for new visitors.
I know this if off topic but I’m looking into starting my own weblog and was
wondering what all is required to get set up? I’m assuming having a blog like yours would
cost a pretty penny? I’m not very internet smart
so I’m not 100% certain. Any suggestions or advice would be
greatly appreciated. Thanks
My family every time say that I am wasting my time here at net, however I know I
am getting familiarity everyday by reading thes fastidious articles.
I’m extremely impressed with your writing skills as well as with the layout on your
weblog. Is this a paid theme or did you customize it yourself?
Either way keep up the nice quality writing, it’s rare to see a great blog like this one these days.
Excellent post. I was checking continuously
this blog and I’m impressed! Very helpful info specially the last part :
) I care for such info a lot. I was looking for this particular info for a long time.
Thank you and good luck.
I waas wondering iif you ever considered changing the structure of your site?
Its very well written; I love what youve got to say.
But maybe you could a little more in the way of content
so people could connect with iit better. Youve got an awful lot oof text for only having 1 or two
images. Maybe you cokuld space it out better?
Hey I know this is off topic but I was wondering if you knew of any widgets I could add to my blog that
automatically tweet my newest twitter updates.
I’ve been looking for a plug-in like this for quite some
time and was hoping maybe you would have some experience with something
like this. Please let me know if you run into anything.
I truly enjoy reading your blog and I look forward to
your new updates.
This is really interesting, You are a very skilled blogger.
I’ve joined your rss feed and look forward to seeking more of your excellent post.
Also, I’ve shared your web site in my social networks!
As the admin of this site is working, no question very rapidly it
will be famous, due to its feature contents.
Hey there! Quick question that’s completely off topic.
Do you know how to make your site mobile friendly?
My website looks weird when viewing from my iphone4.
I’m trying to find a theme or plugin that might be able to fix this problem.
If you have any recommendations, please share.
With thanks!
after getting reply from host B you will get only this entry ” 192.168.6.1 – x.x.x.8916″
answer is D , friends 🙂
P:S: build your own or download the same topology and check by your own self : https://app.box.com/s/hzyjmaxrjjegm3zac9xo
I agree with the answer.