ARP Testlet

for question 4, testking says that the OSI Application layer is what keeps the correct info in each web browser.. this page says that it is the port numbers. which is it? i’ve searched on google to try to find an explanation, but haven’t come up with anything. i did see this exact question on my test last friday… i failed by a handful of points and have a retake thursday morning.

Steve … it is the port numbers that keep those sessions in order. So if you have a yahoo.com page open, google.com open, and amazon.com open the TCP ports (socketing) keep the information going to their correct window.

It is the fact that it is an HTTP window/server that you are trying to open so when DNS resolves that webpage name that you put into the browser window it puts the port number of 80 (being http) onto the end of the IP address so that server knows it is the http portion of the server that you are trying to contact.
So yahoo.com for instance… its name resolves to 69.147.114.224 … and then for the socketing of the port number would make it 69.147.114.224:80.
The IP address of your PC has a dynamic port number added onto it from Windows. So it might be something like 192.168.1.5:4560 (or whatever number the OS puts on there) for each window that you have open that dynamic port number will be a different value, so the next window you have open might be 192.168.1.5:4561
This is how the sessions are kept straight so they go to the proper window. I believe those terms to explain it better would be TCP Sockets or I think also session multiplexing, but I cannot remember exactly.

Thanks for some quality points there. I am kind of new to online , so I printed this off to put in my file, any better way to go about keeping track of it then printing?

yeah nice

9tut, I had a question in the test I took two days ago, what would the switch do if the both the source and destination mac addresses are not in the mac-table ?
please advise.

@ Jay
If the source address is not in the mac (or cam) table, the switch adds it to the table along with the interface on with the packet was received on. If the destination address is also not in the table, the switch will flood the packet out all interfaces except the interface on which that packet was received.

@Ciaran
Your are corret. But the question is listed like this:
The mac table has three mac addresses. for example (A,B,C)
then the question asks what would the switch do if it recieves:
mac address D as a source and
mac address F as a destination
(you have to pick two answers out of five)

@Ciaran
Your are corret. But the question is listed like this:
The mac table has three mac addresses. for example (A,B,C)
then the question asks what would the switch do if it recieves:
mac address D as a source and
mac address F as a destination
(you have to pick two answers out of five)

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@Jay

You mean..
MAC table hads entry for A,B,C.
In coming packet source was D and distination was F?
In that case like Ciaran said
1/ router will flood message to all port except packet source ( which is D situated)
2/ router will update packet source MAC address D to it’s MAC table.

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The answer to what steve posted on February 10th, 2010:

it’s a trick answer. The Transport layer of the OSI model is responsible for source & destination port assignments, not the Application layer.

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Passed ICND1 today with 962…..I didn’t get this ARP testlet on my exam.

Studied with:
Odom ICND1 Book
Todd Lamle CCNA book
Chris Bryant (thebryantadvantage.com)

I didn’t get this questions but there were a lot of questions about the frames that it would be when a PC sends or ping another PC.
Destination MAC address and Source MAC address.

I remember that one question was that what will be the MAC address inside a frame in a ARP when a PC is powered on by first time and it pings another PC. The answer is ff.ff.ff.ff.ff.ff

The above topology is understandable but I have just one question. In question 1, since Host F is trying to reach the Server, and obviously since it’s on a different Lan, when it wants to send a packet to the Server how would it have it’s IP address? It first get’s it’s Mac address from the SFX Router Gateway, I understand that, but how did it get the IP address of the Server? Or does Router SFX always have it??

@bigd
there are 2 ways: you either know the IP from the start or you know the name of the site and you use a DNS server to translate the name to an IP.

short answer: host F knew the IP of the server from the beginning

@Xallax, Thank you.

always a pleasure

@Xallax, taking the exam next week.

@bigd
have you gone through testout’s training? watched the cbt nuggets series for ICND1? read todd lammle’s book? read all the tutorials on 9tut.net?

@ Xallax, Didn’t read Lammle’s book, but I read Cisco Press, I did watch CBT Nuggets and went through this site on a daily basis, as you know. Am I missing something, tutorials?? I read the Q&A’s , if there is something else please let me know. Thanks

@ Xallax, Testout??

create a gmail/yahoo email and post it here, i’ll send you at that address the info for testout

@Xallax, didn’t I give that to you last time? If you can not find I will send it to you again. I don’t like to post on this or any other site if I can avoid it.

that’s why i’ve said to make a new one adkfgslkdhf679823@gmail.com <- perfect!

Look @ ICND experience back to Aug 18.

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Question 2.
I think we need to correct the solution part to ……..
Source addresses: the IP address of host F and the MAC address of host F
Destination addresses: the IP address of WWW server and the MAC address of SFX server

It should be SFX Router and not SFX server. Really important to know.

@Bruno: Yes, thanks for your detection. I updated it!

@xallax and @BIGD ,place mail to vandiepoort@gmail.com the testout taining

Is there any source that explains exactly what happens to a packet at different intervals, the header change etc. For example when it hits a switch or router, does the header change and it if does, why? Little bit out of my depth with this section. Thanks

hello!please anyone can send me the new dump? my email is (posso6@yahoo.com)

hello sir,
i want take ccna exam so pls tell me sugestions

Hello Everyone ! Can anyone please send me the new dump thanks a lot (tssurp@hotmail.com)

Has anyone sat the exam recently? was there many (if any) questions on IPv6?

necr0sys:

Always remember that a frame changes at each hop, but the packet (i.e. source and destination IP address) is never changed or manipulated in any way until it reaches the destination device. MAC addresses are always local. A MAC address will only be used on a local LAN. It will never pass a router’s interface.

For a host to send packets to individual hosts on a local network as well as transmit packets between routers, the Data Link layer uses hardware addressing (MAC addresses). Each time a packet is sent between routers, it’s framed with control information at the Data Link layer (source and destination MAC address), but that information is stripped off at the receiving router and only the original packet is left completely intact. This framing of the packet continues for each hop until the packet is finally delivered to the correct receiving host. It’s really important to understand that the packet itself is never altered along the route; it’s only encapsulated with the type of control information required for it to be properly passed on to the different media types.

The last paragraph came from Lammle’s CCNA Study Guide (6th ed).

There “shouldn’t” be any questions on IPv6 since that isn’t in the list of topics for ICND1 (it is for ICND2).

@hikerdude
yes, they are for ICND2, but you should read about IPv6 at least once. knowledge is power

I am not sure that the answer in Question 4 is correct!?!?

——
Host F is displaying two World Wide Web documents from the WWW server in two browser windows at the same time. How did the data find its way to the correct browser windows?

“C – TCP port numbers are used to direct the data to the correct application window.”
——

In fact HTTP communication is all made on TCP port 80. Which means that it is the SESSION layer that handles this type of communication, which leads that either there is a missing answer here or otherwise the answer here is “B – The browsers track the data by the URL.”

@spirit
nope
the traffic from the host originated on port 12345 and went to port 80 on the web server
then a new browser window was opened and pointed to the web server. the packages had a source port number of 32145 and went on port 80.

you are correct when you say that the communication is done on port 80. the DESTINATION is port 80.
the SOURCE is a number chosen by the host operating system in the range of 1024 ~ 65535 (if i recall right).

happy holidays

Oh yes yes… thank you for reminding me that
I forgot that every time a new session is made that chooses a different source port number > 1024.

SPECIAL THANKS to 9TUT.COM which made it possible for me to pass the ICND1 exam. I am now moving to ICND2.

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I’ll send you a text

Passed ICND1 today. Did not get this on the exam.