TMP Technologies & Infrastructure 3 — Questions and Answers
Question 1: In telecommunications, what is the purpose of a ROADM (Reconfigurable Optical Add-Drop Multiplexer)?
- To amplify electrical signals on copper lines
- To dynamically add, drop, or pass wavelengths in an optical network without converting to electrical signals (Correct answer)
- To route IP packets at Layer 3
- To multiplex DS1 circuits onto a DS3
Correct answer: To dynamically add, drop, or pass wavelengths in an optical network without converting to electrical signals
ROADMs allow operators to remotely reconfigure which wavelengths are added, dropped, or passed through at a node without manual fiber patching.
Question 2: What distinguishes a Class 5 switch from a Class 4 switch in the PSTN hierarchy?
- Class 5 handles only VoIP traffic; Class 4 handles only TDM
- Class 5 is a local exchange connecting end-users; Class 4 is a tandem switch connecting local exchanges (Correct answer)
- Class 4 switches are software-based; Class 5 are hardware-only
- Class 5 operates at higher bandwidth than Class 4
Correct answer: Class 5 is a local exchange connecting end-users; Class 4 is a tandem switch connecting local exchanges
In the traditional PSTN hierarchy, Class 5 switches (local exchanges) connect end-user lines, while Class 4 switches (toll/tandem) interconnect Class 5 offices for long-distance routing.
Question 3: Which access technology uses OFDM modulation and supports both upload and download over a single twisted-pair copper loop up to 500 meters?
- ADSL2+
- G.fast (Correct answer)
- VDSL2
- ISDN BRI
Correct answer: G.fast
G.fast uses OFDM over short copper loops and supports symmetric gigabit-class speeds, making it suitable for fiber-to-the-distribution-point deployments.
Question 4: In a DOCSIS 3.1 cable network, what modulation scheme achieves the highest downstream throughput?
- 64-QAM
- 256-QAM
- 1024-QAM
- 4096-QAM (Correct answer)
Correct answer: 4096-QAM
DOCSIS 3.1 supports up to 4096-QAM, which encodes 12 bits per symbol and enables downstream speeds exceeding 10 Gbps on a single cable plant.
Question 5: A telecom manager must choose between dark fiber and lit fiber services for a new backbone link. What is the key operational difference?
- Dark fiber includes optical amplification; lit fiber does not
- With dark fiber, the customer operates their own optical equipment; lit fiber includes carrier-managed capacity (Correct answer)
- Dark fiber only supports analog signals; lit fiber supports digital
- Lit fiber has lower latency than dark fiber
Correct answer: With dark fiber, the customer operates their own optical equipment; lit fiber includes carrier-managed capacity
Dark fiber is unlit raw fiber where the customer provides and manages all optical transponders and amplifiers, while lit fiber is a managed service where the carrier provides the optical layer.
Question 6: Which IEEE standard governs Power over Ethernet (PoE) delivering up to 30W per port?
- IEEE 802.3af
- IEEE 802.3at (Correct answer)
- IEEE 802.3bt
- IEEE 802.3ac
Correct answer: IEEE 802.3at
IEEE 802.3at (PoE+) extends the original 802.3af standard to deliver up to 30W at the PSE, supporting higher-power devices like PTZ cameras and dual-band APs.
Question 7: What is the role of a Session Border Controller (SBC) in a VoIP network?
- It converts analog signals to digital for VoIP gateways
- It controls and secures VoIP sessions at the border between two networks, handling NAT traversal and security policy enforcement (Correct answer)
- It assigns IP addresses to VoIP phones via DHCP
- It compresses voice codecs to save bandwidth
Correct answer: It controls and secures VoIP sessions at the border between two networks, handling NAT traversal and security policy enforcement
An SBC sits at the peering boundary between networks, enforcing security policies, performing NAT traversal, transcoding, and protecting against VoIP-specific attacks.
TMP Technologies & Infrastructure 3
In telecommunications, what is the purpose of a ROADM (Reconfigurable Optical Add-Drop Multiplexer)?