Switching & VLANs

Which range of VLAN IDs is considered the normal range on a Cisco switch?

• A 0-1005
• B 1-1005 ✓
• C 1-4094
• D 1006-4094

Answer: Normal-range VLANs are 1-1005; extended-range VLANs are 1006-4094.

Which protocol is the IEEE standard for VLAN trunking by inserting a 4-byte tag into the Ethernet frame?

• A ISL
• B 802.1Q ✓
• C VTP
• D LACP

Answer: IEEE 802.1Q is the standard trunking protocol; it inserts a 4-byte tag including the VLAN ID.

On an 802.1Q trunk, which VLAN's traffic is sent untagged by default?

• A VLAN 0
• B The native VLAN ✓
• C VLAN 1005
• D The management VLAN

Answer: Frames on the native VLAN traverse an 802.1Q trunk untagged (default native VLAN is 1).

Which command assigns switchport FastEthernet0/1 to VLAN 20 as an access port?

• A switchport access vlan 20 ✓
• B switchport trunk vlan 20
• C vlan 20 access
• D switchport mode vlan 20

Answer: After setting the port to access mode, 'switchport access vlan 20' places it in VLAN 20.

What information does a switch use to build its MAC address table?

• A Destination IP of incoming packets
• B Source MAC address of incoming frames ✓
• C Destination MAC of outgoing frames
• D ARP requests only

Answer: A switch learns by recording the source MAC address and the port on which each frame arrives.

What does a switch do with a frame whose destination MAC is not in its MAC address table?

• A Drops the frame
• B Floods it out all ports except the one it arrived on ✓
• C Sends it to the default gateway
• D Buffers it until the address is learned

Answer: Unknown unicast frames are flooded out all ports in the VLAN except the ingress port.