Network Design and Implementation Flashcards
7 cards from real STP practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Network Design and Implementation flashcards as text
A network engineer is troubleshooting a switching loop that persists despite STP being enabled. Wireshark shows BPDUs on an access port but the port is in Forwarding state. Which misconfiguration is most likely causing this?
Answer: BPDU Filter enabled on the port
BPDU Filter suppresses both sending and receiving BPDUs on a port, effectively disabling STP on that port and allowing loops if a switch is connected.
In a network design using RSTP, which mechanism allows designated ports to transition to Forwarding without waiting for topology stabilization timers?
Answer: Proposal/Agreement handshake
RSTP uses a point-to-point Proposal/Agreement mechanism between neighboring switches to rapidly transition ports to Forwarding without relying on timers.
A network design requires STP to protect against a downstream switch falsely claiming to be the root bridge. Which feature should be applied to the uplink ports of distribution switches?
Answer: Root Guard
Root Guard on distribution switch uplinks prevents any switch connected downstream from becoming the root bridge by blocking ports that send superior BPDUs.
When designing an STP topology, an engineer wants to ensure that a specific trunk link always remains in the Forwarding state for VLAN 10. Which configuration achieves this?
Answer: Make the switch the root bridge for VLAN 10
If a switch is the root bridge for VLAN 10, all its ports for that VLAN are designated ports and remain in the Forwarding state.
In a network with 48-port access switches uplinked via Gigabit Ethernet to distribution switches, what is the default STP port cost for these Gigabit uplinks using the IEEE long method?
Answer: 20000
Using the IEEE 802.1t long path cost method, a 1 Gbps link has a default cost of 20000, providing finer granularity than the original short method.
A switched network uses PVST+ with the access layer running 802.1D timers. An engineer wants to reduce convergence time without migrating to RSTP. Which adjustment has the greatest impact?
Answer: Reduce the Forward Delay timer on the root bridge
Reducing the Forward Delay timer on the root bridge decreases the time ports spend in Listening and Learning states, directly cutting STP convergence time.
Which STP design scenario can cause a 'bridging loop' even when all switches are running STP correctly?
Answer: A unidirectional link failure where only the receive side fails
If a link fails in only one direction, the affected port stops receiving BPDUs and transitions to Forwarding, while the other end still forwards, creating a loop.