Which of these is a recommended practice with trunks?

Question

Options

• Ause ISL encapsulation
• Buse 802.1q encapsulation
• Cset ISL to desirable and auto with encapsulation negotiate to support ILS protocol negotiation
• Duse VTP server mode to support dynamic propagation of VLAN information across the network

• A
  4% (1)
• B
  85% (23)
• C
  7% (2)
• D
  4% (1)

Explanation

The recommended trunk encapsulation standard is IEEE 802.1Q (Choice B). 802.1Q is an open, vendor-neutral standard that inserts a 4-byte VLAN tag into Ethernet frames and is supported by virtually all modern network equipment. Choice A (ISL) is incorrect-ISL (Inter-Switch Link) is a Cisco-proprietary encapsulation that has been deprecated and is not supported on many current Cisco platforms. Choice C is incorrect-using DTP (Dynamic Trunking Protocol) with 'desirable' and 'auto' modes is a security risk because trunk ports should be statically configured to prevent unauthorized trunk negotiation. Choice D is incorrect-using VTP server mode for dynamic VLAN propagation is generally considered a security and operational risk; a misconfigured VTP server can inadvertently delete VLANs across the network. Best practice is to use 802.1Q with statically configured trunks.

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