erasing the config

Last few mock lab, I had some old config left from whoever last login or was intentional.

I did write erase & reload the router ,On switches I did wr erase & delete vlan.dat file & reload the switch but old Vlan keep coming back up in the c


I am wonering what I am doing wrong ?

Now, I am actual lab how often you need to erase the config ( or this is a it depends answer )

Help me .

Thank you in advance.

Sincererly ,




  • To clear the vlan configuration you will need to either shutdown the trunk links or clear the vlan configuration on all of the switches at the same time.

    If you del vlan.dat and reload one switch, any switch with client or server vtp/vlan configuration connected by a trunk link can cause that switch to inherit the vtp/vlan configuration.

  • Thank you Darrell,

    Now it make sense why those vlan keep coming back. I guess , I did not think all the option( Or I assumed that those trunk links are shut down). How about Actual Lab Strategy ?

    I think look for any kind of preconfiguration & match & if you think it's easy to erase & start from scrartch.

    Once again ,

    Thank you


  • During the Lab Exam you _don't_ want to erase the initial configs - some people advise saving the initial configs to a Notepad/.txt file to make sure you don't lose the configs you were given. The proctor probably will not be very happy if he has to provide the initial configs for you. If he is willing to do this at all, he will probably apply the initial configs to _all_ of your devices, so all of your work will be lost.

    The first thing you want to do with your equipment is to verify that the initial configuration matches your lab diagram and tasks.

    Show ip int brief or show protocols on each device to verify that you have the correct IP addresses preconfigured.

    Show frame-relay map to verify the frame-relay DLCIs and IP addresses match your diagram and lab tasks.

    If the initial configs do not match, go to the proctor ASAP - if you wait you will not get credit for wasted time. You should not need to _change_ much of the initial configs - you will need to add other configuration to make the tasks work.

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