WertzHills255

CCNA and CCNP candidates who have their own Cisco residence labs typically email me about an odd situation that happens when they erase a switch's configuration. Their startup configuration is gone, as they anticipate, but the VLAN and VTP details is still there!

Sounds odd, doesn't it? Let's look at an example. On SW1, we run display vlan short and see in this abbreviated output that there are 3 further vlans in use:

SW1#display vlan br

10 VLAN0010 active

20 VLAN0020 active

30 VLAN0030 active

We want to completely erase the router's startup configuration, so we use the write erase command, confirm it, and reload with no saving the running config:

SW1#create erase

Erasing the nvram filesystem will eliminate all configuration files! Continue?

[confirm]

[OK]

Erase of nvram: comprehensive

00:06:00: %SYS-7-NV_BLOCK_INIT: Initalized the geometry of nvram

SW1#reload

Technique configuration has been modified. Save? [yes/no]: n

Proceed with reload? [confirm]

The router reloads, and following exiting setup mode, we run show vlan short once again. And even even though the startup configuration was erased, the vlans are still there!

Switch#show vlan br

10 VLAN0010 active

20 VLAN0020 active

30 VLAN0030 active

The cause is that this vlan and VTP data is actually kept in the VLAN.DAT file in Flash memory, and the contents of Flash are kept on a reload. The file has to be deleted manually.

There's a small trick to deleting this file. The switch will prompt you twice to ask if you genuinely want to get rid of this file. Do not variety "y" or "yes" just accept the defaults by hitting the return important. If you sort "y", the router attempts to delete a file named "y", as shown right here:

Switch#delete vlan.dat

Delete filename [vlan.dat]? y

Delete flash:y? [confirm]

%Error deleting flash:y (No such file or directory)

Switch#delete vlan.dat

Delete filename [vlan.dat]?

Delete flash:vlan.dat? [confirm]

Switch#

The best way to prepare for CCNA and CCNP exam accomplishment is by operating on genuine Cisco equipment, and by performing lab tasks over and over. Repetition is the mother of skill, and by really erasing your VLAN and VTP details by deleting the vlan.dat file from Flash, you'll be creating your Cisco skills to the point exactly where your CCNA and CCNP exam achievement is a certainty. honda motorcycles