VTP Interview Questions and Answers
What are the requirements to exchange VTP messages between two switches? 1. A switch should be configured as either a VTP server or VTP client. 2. VTP domain name must be same on both switches. 3. VTP versions must match. 4. The link between the switches should be a trunk link.
What is VTP Pruning? VLAN Trunking Protocol (VTP) pruning is a feature in Cisco switches, which stops VLAN update information traffic from being sent down trunk links if the updates are not needed. Broadcast frames, multicast frames or unicast frames for which the destination MAC address is unknown are forwarded over a trunk link only if the switch on the receiving end of the trunk link has ports in the source VLAN. This avoids unnecessary flooding. VLAN 1 can never prune because it’s an administrative VLAN.
What are different VTP modes? VTP Server mode – By default, every switch is in server mode. Switch in VTP Server Mode can create, delete VLANs and will propagate VLAN changes. VTP Client mode – Switch in VTP client mode cannot create or delete VLANs. VLAN Trunking Protocol (VTP) client mode switches listen to VTP advertisements from other switches and modify their VLAN configurations accordingly. It listens and forwards updates. VTP Transparent mode – Switch in VTP Transparent mode does not share its VLAN database but it forwards received VTP advertisements. we can create and delete VLANs on a VTP transparent switch but these changes are not sent to other switches.
List of VTP Interview Questions
Below is the list of top interview questions asked related to VTP technology:
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Ans.
Change in Revision number is different
In first option, Revision no. gets increased by 3
In second option, Revision no. gets increased by 1
Reference Video: starts at 28:00
15. Two Switches are in VTP Server mode with different VLAN’s. Revision Number of both the switches is 0. Which switch will overwrite his own VLAN Database onto other, if both switches are in the same VTP Domain?
Ans.
The one where change is performed first; Both switches don’t do anything until you add or remove any vlans, so that revision number goes up; then that switch will push vlans onto the other one
16. Scenario: We have Switch A in Server mode with Revision number 10 & another Switch B in Client mode with Revision number 20. Who will win & overwrite the another’s Switch VLAN database ?
Ans.
In any case, Revision number always takes the precedence. That’s why it is recommended to add new switch in the network with revision number as ZERO. So, Switch B will overwrite the database of Switch A.
17. If a Switch is in Client mode, Can we enter into the configuration mode ?
Ans.
18. By the statement, ” VLAN is down “. What to conclude from this statement ?
Ans. If a Vlan is down, it simply means that Physical ports associated with the VLAN are down.
Example Scenario
Sep 2 07:29:25 EDT: %LINK-3-UPDOWN: Interface Vlan100, changed state to down Sep 2 07:29:25 EDT: %LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan100, changed state to down
core#sh int des | i Gi7/2 Gi7/2 down down Connection to switch
Comment
Gi 7/2 is the port assigned to VLAN 100, Gi7/2 is in down state.
19. If a VLAN interface or SVI went down & we want to make the VLAN interface or SVI to be up forcefully.
How to do that & in which scenario, this will be required ?
Ans.
Command to make interface VLAN to be up forcefully,
” no autostate ” under SVI interface.
Scenario
We use it on cisco 800 series CPE ( Customer Premises Equipment ) to verify internet reachability from lan interface, when customer lan is not connected.
And this is just for testing only as it is not recommended to keep autostate off on svi port. Advertisement
FAQ
What are the 3 VTP modes?
- VTP client mode – a switch using this mode can’t change its VLAN configuration. …
- VTP server mode – a switch using this mode can create and delete VLANs. …
- VTP transparent mode – a switch using this mode doesn’t share its VLAN database, but it forwards received VTP advertisements.
What is the purpose of VTP?
How many types of VTP are there?
