CCNA CCNP Home Lab Tutorial The VLAN.DAT File
Below is a MRR and PLR article in category Computers Technology -> subcategory Computer Certification.
CCNA/CCNP Home Lab Tutorial: Understanding the VLAN.DAT File
Overview
For many CCNA and CCNP candidates, a common confusion arises when VLAN and VTP information remain on a switch even after erasing its configuration. This guide explains why this happens and how to completely remove VLAN information, courtesy of Chris Bryant, CCIE
12933.
Why VLAN Information Persists
Many aspiring network professionals contact me when they erase a switch's configuration only to find that while the startup configuration is removed, VLAN and VTP information persists. Let’s delve into why that is and how to address it.
Example Scenario
On a switch labeled SW1, executing the `show vlan brief` command might reveal the presence of additional VLANs:
```
SW1
show vlan br
10 VLAN0010 active
20 VLAN0020 active
30 VLAN0030 active
```
To erase the switch's configuration, you might use:
```
SW1
write erase
Erasing the nvram filesystem will remove all configuration files! Continue?[confirm]
[OK]
Erase of nvram: complete
SW1
reload
System configuration has been modified. Save? [yes/no]: nProceed with reload? [confirm]
```
After reloading, and exiting setup mode, you'd expect everything to be gone. However, running `show vlan brief` again reveals the VLANs are still there.
The Reason
This phenomenon occurs because VLAN and VTP information is stored in the VLAN.DAT file in Flash memory, which isn't erased with a standard reload.
Deleting the VLAN.DAT File
To truly remove VLAN information, you must manually delete the VLAN.DAT file. Here's a key trick: When prompted, do not type "y" or "yes." Simply press the return key to accept defaults. Typing "y" triggers a failed attempt to delete a non-existent file named "y":
```
Switch
delete vlan.dat
Delete filename [vlan.dat]? yDelete 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]
```
Building Skills for Exam Success
Regular practice with real Cisco equipment enhances your readiness for CCNA and CCNP exams. By repeatedly deleting the VLAN.DAT file and ensuring thorough erasure of VLAN and VTP information, you’ll sharpen your skills, paving the way for certification success.
You can find the original non-AI version of this article here: CCNA CCNP Home Lab Tutorial The VLAN.DAT File.
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