CCNA / CCNP Home Lab Tutorial: The VLAN.DAT File
CCNA and CCNP candidates who have their own Cisco home labs often email me about an odd situation that occurs when they erase a switch’s configuration. Their startup configuration is gone, as they expect, but the VLAN and VTP information is still there!
Sounds strange, doesn’t it? Let’s look at an example. On SW1, we run show vlan brief and see in this abbreviated output that there are three additional vlans in use:
SW1#show vlan br
10 VLAN0010 active
20 VLAN0020 active
30 VLAN0030 active
We want to totally erase the router’s startup configuration, so we use the write erase command, confirm it, and reload without saving the running config:
SW1#write erase
Erasing the nvram filesystem will remove all configuration files! Continue?
[confirm]
[OK]
Erase of nvram: complete
00:06:00: %SYS-7-NV_BLOCK_INIT: Initalized the geometry of nvram
SW1#reload
System configuration has been modified. Save? [yes/no]: n
Proceed with...
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