Objectives 5.2

Question 1

Which issue occurs when the wrong type of network cable is used for a connection?
- Error disabled
- Crosstalk
- Incorrect cable
- Attenuation

Answer 1

Incorrect cable | Practical Use: Using a crossover cable instead of a straight-through cable for a switch. | Explanation: Wrong cable type causes failures, reduced performance, or no link. | Objective: 5.2 – Cable issues | Follow-up Question: Why is using Cat6 better than Cat5 for gigabit networks?

Question 2

Which fiber type is designed for long distances with a small core size?
- Multimode fiber
- Single-mode fiber
- Coaxial
- UTP

Answer 2

Single-mode fiber | Practical Use: Connecting buildings across a campus. | Explanation: Single-mode fiber supports higher bandwidth and less attenuation over distance. | Objective: 5.2 – Cable issues | Follow-up Question: Why would multimode fiber fail at very long distances?

Question 3

What happens if Cat5 cable is used instead of Cat6 for gigabit Ethernet?
- Limited speeds and higher errors
- Network still works with no effect
- Less attenuation
- Stronger security

Answer 3

Limited speeds and higher errors | Practical Use: Cat5 cable capping performance below gigabit. | Explanation: Using lower category cables reduces performance and reliability. | Objective: 5.2 – Cable issues | Follow-up Question: What category of cable supports 10 Gbps at short distances?

Question 4

When should shielded twisted pair (STP) be used instead of unshielded twisted pair (UTP)?
- In areas with high EMI
- For connecting fiber devices
- Always in home networks
- For short patch cables

Answer 4

In areas with high EMI | Practical Use: Data center cabling near power lines. | Explanation: STP protects signals from electromagnetic interference. | Objective: 5.2 – Cable issues | Follow-up Question: Why might UTP still be preferred in low-interference environments?

Question 5

What is signal degradation?
- Weakening of signal over distance or interference
- Firewall blocking packets
- Wrong category of cable used
- A device losing power

Answer 5

Weakening of signal over distance or interference | Practical Use: Long copper cable runs losing quality. | Explanation: Degraded signals cause errors, slow transfer rates, or drops. | Objective: 5.2 – Signal degradation | Follow-up Question: How can repeaters help against signal degradation?

Question 6

Which type of interference occurs when signals from one cable leak into another?
- Crosstalk
- Interference
- Attenuation
- Improper termination

Answer 6

Crosstalk | Practical Use: Poorly twisted cables leaking signals. | Explanation: Crosstalk corrupts data and reduces transmission speeds. | Objective: 5.2 – Signal degradation | Follow-up Question: What’s the difference between NEXT and FEXT?

Question 7

What kind of disruption is caused by nearby electronic devices affecting a cable?
- Runts
- Giants
- EMI/RFI interference
- Attenuation

Answer 7

EMI/RFI interference | Practical Use: A network cable near a microwave. | Explanation: External signals disrupt transmission, causing data loss. | Objective: 5.2 – Signal degradation | Follow-up Question: How can shielding reduce EMI?

Question 8

What is attenuation in cabling?
- Crosstalk between pairs
- Transceiver mismatch
- Loss of signal strength over distance
- Packets smaller than 64 bytes

Answer 8

Loss of signal strength over distance | Practical Use: Long copper cable runs requiring repeaters. | Explanation: Attenuation weakens signals and reduces performance. | Objective: 5.2 – Signal degradation | Follow-up Question: Why is fiber less affected by attenuation than copper?

Question 9

What issue results from cables not being properly connected or terminated?
- Improper termination
- Crosstalk
- CRC errors
- Attenuation

Answer 9

Improper termination | Practical Use: Mis-crimped RJ45 connector. | Explanation: Bad termination causes signal reflection and EMI. | Objective: 5.2 – Cable issues | Follow-up Question: How can a cable tester help detect termination problems?

Question 10

What happens if transmitter (TX) and receiver (RX) wires are swapped?
- Signal strength improves
- PoE stops working
- No communication link is established
- Crosstalk occurs

Answer 10

No communication link is established | Practical Use: Fiber patch cables installed backward. | Explanation: TX/RX transposed prevents devices from linking properly. | Objective: 5.2 – Cable issues | Follow-up Question: What tool can help verify proper TX/RX alignment?

Question 11

Which error occurs when a packet checksum doesn’t match during transmission?
- CRC error
- Giant
- Runt
- Drop

Answer 11

CRC error | Practical Use: Corrupt packet retransmissions caused by EMI. | Explanation: CRC errors indicate data corruption. | Objective: 5.2 – Interface issues | Follow-up Question: What cable issue often leads to CRC errors?

Question 12

What is a runt frame?
- A corrupted checksum
- A packet larger than 1518 bytes
- A packet smaller than 64 bytes
- A signal reflection

Answer 12

A packet smaller than 64 bytes | Practical Use: Collision causing undersized frames. | Explanation: Runts waste bandwidth and cause processing overhead. | Objective: 5.2 – Interface issues | Follow-up Question: What typically causes runt frames?

Question 13

What is a giant frame?
- A frame with swapped TX/RX
- A packet with a failed checksum
- A small corrupted packet
- A packet larger than the maximum Ethernet size

Answer 13

A packet larger than the maximum Ethernet size | Practical Use: Faulty NIC generating oversized frames. | Explanation: Giants exceed standard Ethernet size, causing issues. | Objective: 5.2 – Interface issues | Follow-up Question: What’s the maximum size for a normal Ethernet frame?

Question 14

What does it mean when packets are being dropped?
- They are too small to transmit
- They are larger than 1518 bytes
- They are discarded due to congestion or buffer overflow
- They are retransmitted successfully

Answer 14

They are discarded due to congestion or buffer overflow | Practical Use: Router discarding packets during high traffic. | Explanation: Drops occur when devices can’t process traffic in time. | Objective: 5.2 – Interface issues | Follow-up Question: How do QoS policies help reduce drops?

Question 15

What does it mean if a switch port is error disabled?
- It is receiving interference
- It was manually disabled by an admin
- It is suspended for policy reasons
- It has been automatically shut down due to a problem

Answer 15

It has been automatically shut down due to a problem | Practical Use: Port shutdown after a security violation. | Explanation: Error disabled prevents faults from spreading. | Objective: 5.2 – Interface issues | Follow-up Question: What event could trigger error-disabled status?

Question 16

What does “administratively down” mean for a port?
- It is waiting for a cable to be plugged in
- It is misconfigured
- It was manually disabled by an administrator
- It was shut down automatically after an error

Answer 16

It was manually disabled by an administrator | Practical Use: Shutting a port during maintenance. | Explanation: Admins disable ports for security or reconfiguration. | Objective: 5.2 – Interface issues | Follow-up Question: Why would an admin intentionally disable a port?

Question 17

What does it mean if a port is suspended?
- It is dropping packets due to buffer overflow
- It is in error-disabled mode
- It is permanently shut down by admin
- It is temporarily disabled due to a policy violation or protocol action

Answer 17

It is temporarily disabled due to a policy violation or protocol action | Practical Use: LACP policy disabling a link temporarily. | Explanation: Suspended ports are held inactive until policies are corrected. | Objective: 5.2 – Interface issues | Follow-up Question: How does suspension differ from error-disabled status?

Question 18

What happens when the PoE power budget is exceeded on a switch?
- Ports automatically become administratively down
- Devices may not power on or work intermittently
- Attenuation is reduced
- Frames become runts

Answer 18

Devices may not power on or work intermittently | Practical Use: Too many IP cameras drawing PoE from a switch. | Explanation: Exceeding budget leaves insufficient power for devices. | Objective: 5.2 – Hardware issues | Follow-up Question: How can upgrading hardware resolve PoE budget issues?

Question 19

What issue occurs if PoE devices and switches use different standards?
- Attenuation increases
- Devices fail to receive proper power
- Interfaces drop packets
- Runts appear

Answer 19

Devices fail to receive proper power | Practical Use: Mixing 802.3af and 802.3bt equipment. | Explanation: Incompatible standards prevent devices from powering. | Objective: 5.2 – Hardware issues | Follow-up Question: What are common PoE standards in use today?

Question 20

What problem occurs if transceivers from different vendors are mismatched?
- Port suspension
- No link light or data errors
- Runt frames
- Improper termination

Answer 20

No link light or data errors | Practical Use: Incompatible fiber transceivers preventing connectivity. | Explanation: Transceiver mismatches cause intermittent or failed links. | Objective: 5.2 – Hardware issues | Follow-up Question: Why is it recommended to use vendor-matched transceivers?

Question 21

What issue results from poor signal strength in a transceiver?
- Attenuation improves
- High error rates or dropped packets
- CRC errors disappear
- Ports go into admin down state

Answer 21

High error rates or dropped packets | Practical Use: Dirty fiber connectors causing signal loss. | Explanation: Weak transceiver signals reduce performance. | Objective: 5.2 – Hardware issues | Follow-up Question: How can cleaning fiber connectors improve signal strength?