VTP and MAC Question

[teacher813]

I'm having a problem with one of my questions for my CCNA lab. The question is "How do you determine where a VTP update originate from? What command do you use on your client switch?" The situation is that your switch is the client and there are 3 other switches, so how can you find out where a VTP update originated from.

Also, What command do you use to show which port a particular MAC address will be sent out? So if a MAC address was learned on a certain port, how do you display that information?

I failed the CCNA test the other day by 5 points. I got a 842 out of 847

 

[jimfixit]

The command to find what port is associated with a mac address is:
show mac-address-table <option> Options are many but the most usable for me have been "address < followed by the mac address to locate>" or "dynamic". The output from this will be similar to:
Mac Address Table
-------------------------------------------

Vlan Mac Address Type Ports
---- ----------- -------- -----
1 0000.0000.fe00 DYNAMIC Po8
1 0000.0000.fe01 DYNAMIC Po8
1 0000.5e00.0114 DYNAMIC Po8
1 0000.8509.a575 DYNAMIC Gi3/0/15

and there you can see the port channel (in my example) or physical interface for a given mac address.

If you know the IP address you can ping it then issue the following:

show arp | beg <ip address> and that will show you as the first line of out put the exact mac address. Like so:

ping 10.1.111.64
RouterA#show arp | beg 10.1.111.64
Internet 10.1.111.64 0 000d.c808.2d11 ARPA Vlan1
Internet 10.1.1.50 134 0005.74e2.acc0 ARPA Vlan1
Internet 10.1.113.59 34 0011.43c3.a38c ARPA Vlan1
Internet 10.1.1.69 0 0018.8bb8.77f8 ARPA Vlan1
Internet 10.1.99.4 7 0014.c2c3.1a5d ARPA Vlan1
Internet 10.1.117.234 4 000d.c808.2d10 ARPA Vlan1
Internet 10.1.112.198 0 000d.c808.19fa ARPA Vlan1

This also tells you the vlan that ip address is on along with mac address.


to determine where an update came from turn on spanning tree debuging:

debug spanning-tree <options>. There are lots of these options but you can use 'all' to see all the messages or use events...or use the ? and look over the options to narrow down your output.

 

[NetworksMD]

I think the answer that they are looking for is show VTP status. If you look at the bottom of the output you will see Configuration last modified by [IP ADDRESS OF SERVER] at [Date] [Time].

 

[teacher813]

Guess what, I just took the CCNA test again. 809 out of 1000 this time. This is the 3 time i have failed this test.
AGGGHHHH!!!!

Now that ive got that off my chest... One of the questions in my lab that i failed is related to the above question, but i tell you the question again in detailed:

The situation is that you are logged onto 1 of 4 switches and you need to find out the NAME of the switch where the VTP update originated from. Once again, YOU NEED TO FIND OUT THE NAME OF THE SWITCH; NOT THE IP ADDRESS. I ran the "show vtp status" command and i got the IP address, but how do i translate the IP into a name? Do i use reverse arp?

One more question, what is the best way to study and pass the CCNA?

 

[lerdalt]

My best guess on finding the name of the switch is from the show vtp status command get the ip address then try to connect to it. Otherwise maybe use show cdp neighbors detail?

Back to the mac address question, if I remember right, the CCNA exams really want you to use the following command:
show mac-address-table dynamic address xxxx.xxxx.xxxx

As for the best way to study and pass, check out the cisco certification and testing forum. There are quite a few people out there right now that have been struggling to get through, and some really good people out there to get more answers from. Recommended reading is the Todd Lammle book from Sybex. I'd also recommend getting your hands on some equipment and lab some things out just to help get a better understanding.

Just don't get frustrated. There are tons of people out there that had to take these tests multiple times before they pass. You are close, just keep plugging away.

 

[dtrtel]

I remember that darn simlet. It cost me my first round at the CCNA combined exam. I think I used the show vtp status and looked for last modified by. Then show cdb neighbor detail to get the name. I don't know if I got it right though. But time management is a critical part of the exam. I think that simlet was the most complicated thing on the exam. Be solid on the rest and you might get by guessing your way through on a few. At any rate, if you scratch your head too long on anything, you will fail. Don't try to be perfect. First time, 700-something, second time 936 using that strategy.

--jeff

http://linkedin.com/in/JeffLynch