Objectives 5.3

Question 1

Which protocol prevents network loops by blocking redundant paths?
- DHCP
- VLAN
- OSPF
- STP

Answer 1

STP (Spanning Tree Protocol) | Practical Use: Preventing broadcast storms between redundant switch links. | Explanation: STP ensures loop-free logical topologies. | Objective: 5.3 – Switching issues | Follow-up Question: What happens when STP is misconfigured?

Question 2

What determines which switch becomes the root bridge in STP?
- Fastest port
- Default route
- Lowest bridge ID
- Highest MAC address

Answer 2

Lowest bridge ID | Practical Use: Choosing a central switch to optimize traffic flow. | Explanation: Root bridge is elected using priority + MAC. | Objective: 5.3 – Switching issues | Follow-up Question: How can admins influence which switch becomes the root bridge?

Question 3

Which STP port role represents the best path to the root bridge?
- Suspended Port
- Blocked Port
- Root Port
- Designated Port

Answer 3

Root Port | Practical Use: Ensures traffic flows along the best path to the root bridge. | Explanation: Root Ports connect directly toward the root bridge. | Objective: 5.3 – Switching issues | Follow-up Question: What role prevents loops by not forwarding traffic?

Question 4

Which STP port state actively forwards traffic?
- Learning
- Blocking
- Listening
- Forwarding

Answer 4

Forwarding | Practical Use: Port forwarding frames after STP convergence. | Explanation: STP transitions ports through states to ensure stability. | Objective: 5.3 – Switching issues | Follow-up Question: What is the purpose of the listening state?

Question 5

What problem occurs if a device is placed in the wrong VLAN?
- Incorrect VLAN assignment
- Loopback failure
- Duplicate IP address
- Incorrect subnet mask

Answer 5

Incorrect VLAN assignment | Practical Use: Devices unable to communicate with intended group. | Explanation: Wrong VLAN breaks segmentation and can expose sensitive data. | Objective: 5.3 – Switching issues | Follow-up Question: How can VLAN audits prevent this issue?

Question 6

What happens if an ACL is misconfigured?
- STP root bridge fails
- VLANs will collapse
- Routing tables will corrupt
- Legitimate traffic may be blocked or unauthorized traffic allowed

Answer 6

Legitimate traffic may be blocked or unauthorized traffic allowed | Practical Use: Users unable to access email due to ACL error. | Explanation: ACLs filter traffic, and mistakes cause connectivity/security issues. | Objective: 5.3 – Switching issues | Follow-up Question: How can regular ACL audits improve security?

Question 7

What problem occurs when routing tables contain stale or misconfigured routes?
- Incorrect default gateway
- Routing table issue
- CRC error
- VLAN mismatch

Answer 7

Routing table issue | Practical Use: Router forwarding packets incorrectly. | Explanation: Outdated/misconfigured routes cause packet loss or loops. | Objective: 5.3 – Route selection | Follow-up Question: How can stale routes be corrected?

Question 8

What is the result of a missing or incorrect default route?
- VLANs stop working
- STP ports block
- DHCP pool runs out
- Packets destined for unknown networks are dropped

Answer 8

Packets destined for unknown networks are dropped | Practical Use: Users unable to reach external websites. | Explanation: Default routes handle traffic to destinations not in routing table. | Objective: 5.3 – Route selection | Follow-up Question: Why can over-reliance on default routes be a problem?

Question 9

What happens when a DHCP pool is exhausted?
- Routing tables misconfigure
- VLANs collapse
- Devices fail to receive IP addresses
- Packets drop at the switch

Answer 9

Devices fail to receive IP addresses | Practical Use: Too many clients requesting addresses on a small subnet. | Explanation: Exhausted DHCP scopes leave devices without connectivity. | Objective: 5.3 – Addressing issues | Follow-up Question: How can subnet expansion fix this?

Question 10

What happens if devices have an incorrect default gateway?
- They cannot receive DHCP leases
- They cannot reach external networks
- STP blocks ports
- VLANs stop forwarding

Answer 10

They cannot reach external networks | Practical Use: Workstations unable to access the internet. | Explanation: Default gateway directs traffic to outside networks. | Objective: 5.3 – Addressing issues | Follow-up Question: Why must the default gateway be in the same subnet as the host?

Question 11

What happens if a device is assigned the wrong IP address?
- It becomes the root bridge
- It creates routing loops
- It cannot communicate properly on the network
- It blocks all ACLs

Answer 11

It cannot communicate properly on the network | Practical Use: Typo in static IP preventing access. | Explanation: Incorrect IPs cause communication failures. | Objective: 5.3 – Addressing issues | Follow-up Question: How can DHCP reservations help prevent this?

Question 12

What issue arises when two devices share the same IP address?
- Duplicate IP address conflict
- VLAN misconfiguration
- Routing loop
- Incorrect subnet mask

Answer 12

Duplicate IP address conflict | Practical Use: Two printers with the same static IP. | Explanation: Duplicate IPs cause network instability and dropped traffic. | Objective: 5.3 – Addressing issues | Follow-up Question: What tools can detect duplicate IP addresses?

Question 13

What happens if a device has an incorrect subnet mask?
- Devices cannot communicate properly within the network
- DHCP pool is exhausted
- STP blocks redundant links
- VLANs collapse

Answer 13

Devices cannot communicate properly within the network | Practical Use: Host with 255.255.0.0 mask can’t talk to /24 subnet. | Explanation: Incorrect subnetting breaks local communication. | Objective: 5.3 – Addressing issues | Follow-up Question: How does subnetting affect broadcast domains?