Network+ Ethernet Switching and VLANs Flashcards

A network technician is configuring a switch port that will connect to another switch. The link needs to carry traffic for multiple VLANs simultaneously. Which type of port configuration should the technician use?

Answer: Trunk port

A trunk port is specifically designed to carry traffic for multiple VLANs between network devices like switches. [1, 2, 5] An access port, by contrast, is configured to carry traffic for only a single VLAN, typically for connecting end devices like PCs or printers. [2, 6] Spanning Tree is a protocol, not a port type, and a mirrored port is used for network monitoring.

Which IEEE standard defines the protocol for VLAN tagging, which adds a 4-byte header to an Ethernet frame to identify the VLAN?

Answer: 802.1Q

The IEEE 802.1Q standard defines the system of VLAN tagging for Ethernet frames. [9, 14, 21] This standard specifies the addition of a 4-byte tag into the frame header to identify the VLAN to which the frame belongs. [11, 14, 21] 802.1D is the original Spanning Tree Protocol, 802.3af relates to Power over Ethernet (PoE), and 802.11ac is a Wi-Fi standard.

A network administrator is configuring a trunk link between two switches. The administrator wants to specify a VLAN that will handle all untagged traffic. What is this type of VLAN called?

Answer: Native VLAN

The Native VLAN is the VLAN to which a trunk port assigns untagged traffic. [3, 7, 12] By default, this is often VLAN 1, but for security reasons, it's best practice to change it. [12, 16] While a management VLAN is used for device administration and the default VLAN is the initial VLAN for all ports, the specific function of carrying untagged traffic on a trunk belongs to the Native VLAN. [16]

In a switched network with redundant links between switches, which protocol is used to prevent switching loops and broadcast storms by logically blocking certain paths?

Answer: STP (Spanning Tree Protocol)

The Spanning Tree Protocol (STP) is designed to prevent bridge loops and the resulting broadcast storms in networks with redundant paths. [20, 22, 27] It does this by creating a loop-free logical topology, placing some ports in a blocking state to eliminate redundant links while keeping them available as backups. [20, 25, 27]

A junior technician is configuring two Cisco switches to automatically negotiate a trunk link between them. One switch port is configured with the Dynamic Trunking Protocol (DTP) mode 'dynamic desirable'. For a trunk link to be successfully formed, which DTP mode can the port on the second switch be configured to?

Answer: Dynamic Auto

Dynamic Trunking Protocol (DTP) is a Cisco-proprietary protocol for negotiating trunk links. [4, 8, 10] When one side is 'dynamic desirable', it actively tries to form a trunk. It can successfully form a trunk with a port configured as 'trunk', 'dynamic desirable', or 'dynamic auto'. [4, 17] A port in 'access' mode will not form a trunk. [4, 10] 'Spanning Tree' and 'VTP Client' are not DTP modes.

A network administrator wants to centrally manage VLAN information (creation, deletion, and renaming) and have those changes automatically propagated to all other switches in the network. Which Cisco proprietary protocol facilitates this function?

Answer: VTP (VLAN Trunking Protocol)

VLAN Trunking Protocol (VTP) is a Cisco proprietary protocol that synchronizes VLAN information across switches within the same VTP domain. [23, 28, 30] A switch configured as a VTP server can be used to create, modify, or delete VLANs, and these changes are then advertised to all other switches in the domain, simplifying administration. [29, 30, 33]