The network administrator is trying to add Switch1 to the network, but the 802.1 Q trunk is not coming up. Switch1 was previously tested in the laboratory and its trunk configuration worked fine…

Question

Exhibit

Options

• AThe trunking configuration mode on Switch1 is set to Off.
• BThe trunking configuration mode on the other end is set to On.
• CThe trunking configuration mode on the other end is set to Desirable.
• DCisco Discovery Protocol is not running on the other end.
• EThere is a VTP domain name mismatch.
• FSwitch1 does not support 802.1Q.

• A
  78% (29)
• B
  5% (2)
• C
  11% (4)
• D
  5% (2)

Explanation

There are 5 possible trunking modes for a switch port: Auto: this is the default mode. In this mode, a port will become a trunk port if the device the port is connected to is set to the on or desirable mode. Desirable: allows the port to become a trunk port if the device the port is connected to is set to the on, desirable, or auto mode On: sets the port to permanent trunking mode. Nonegotiate: sets the port to permanent trunking mode without sending Dynamic Trunking Frame Off: sets the port to permanent non-trunking mode In this case, we can guess the trunking mode of Switch 1 is auto (default mode). When in the laboratory, the trunking mode of the other end is set to On or Desirable so 2 switches can negotiate and the link becomes trunk with no problem. But when plugging to the network, other switches may have the trunking mode set to auto so the 802.1Q trunk is not coming up Of course these switches need to be in the same VTP domain so that they can talk with each other. When trying to configure a trunk negation with a mismatched VTP domain you will receive the following error %DTP-5-DOMAINMISMATCH: Unable to perform trunk negotiation on port Gig0/1 because of VTP domain mismatch. Cisco General Networking Theory Quick Reference Sheets

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