CTE Telecommunications Infrastructure & Network Management 3 — Questions and Answers
Question 1: A network executive is reviewing the SLA for a leased transport circuit. The SLA specifies 99.999% availability. Approximately how many minutes of downtime per year does this allow?
- 52.6 minutes
- 8.76 hours
- 5.26 minutes (Correct answer)
- 43.8 minutes
Correct answer: 5.26 minutes
Five nines (99.999%) availability translates to approximately 5.26 minutes of allowable downtime per year.
Question 2: When deploying a new IP/MPLS backbone, which IGP is preferred by most large carriers due to its scalability and fast convergence?
- RIPv2
- EIGRP
- IS-IS (Correct answer)
- IGRP
Correct answer: IS-IS
IS-IS is widely preferred by large carriers for IP/MPLS backbones because of its scalability, flexibility, and fast convergence characteristics.
Question 3: What does MTTR measure in the context of network infrastructure management?
- Mean Time To Replicate — how fast a config propagates
- Mean Time To Repair — average time to restore a failed component (Correct answer)
- Maximum Threshold for Traffic Routing
- Minimum Topology Transition Rate
Correct answer: Mean Time To Repair — average time to restore a failed component
MTTR (Mean Time To Repair) measures the average time required to restore a failed network component or service to normal operation.
Question 4: A telecommunications executive is designing network capacity for a region experiencing 40% annual traffic growth. Which planning approach best addresses this?
- Reactive expansion only when congestion occurs
- Proactive capacity planning with 18–24 month demand forecasts (Correct answer)
- Freezing capacity and prioritizing QoS throttling
- Outsourcing all capacity decisions to equipment vendors
Correct answer: Proactive capacity planning with 18–24 month demand forecasts
Proactive capacity planning with 18–24 month forecasts ensures infrastructure keeps pace with demand, avoiding costly emergency upgrades.
Question 5: In telecommunications, what is the purpose of a Digital Cross-Connect System (DCS)?
- Encrypting voice traffic at the PSTN gateway
- Grooming and routing digital signals between transmission facilities (Correct answer)
- Providing DHCP addressing to DSL subscribers
- Managing billing records for wholesale carriers
Correct answer: Grooming and routing digital signals between transmission facilities
A DCS grooms, multiplexes, and routes digital signals (DS0–DS3/OC-n) between transmission facilities without converting to analog.
Question 6: Which technology enables multiple virtual private networks to share a common MPLS backbone while maintaining traffic isolation?
- ATM PVCs
- L3VPN using BGP/MPLS (Correct answer)
- Frame Relay DLCIs
- ISDN B-channels
Correct answer: L3VPN using BGP/MPLS
BGP/MPLS Layer 3 VPNs (RFC 4364) allow multiple customer VPNs to share MPLS infrastructure with full routing and traffic isolation.
Question 7: A CTE is evaluating whether to deploy SDH or PDH for a new regional transport network. What is the key advantage of SDH over PDH?
- SDH uses less bandwidth per circuit than PDH
- SDH provides standardized overhead for network management and built-in protection switching (Correct answer)
- SDH eliminates the need for fiber optic cabling
- SDH supports only voice traffic, reducing complexity
Correct answer: SDH provides standardized overhead for network management and built-in protection switching
SDH provides standardized section, line, and path overhead enabling sophisticated network management, performance monitoring, and automatic protection switching.
CTE Telecommunications Infrastructure & Network Management 3
A network executive is reviewing the SLA for a leased transport circuit.
The SLA specifies 99.999% availability.
Approximately how many minutes of downtime per year does this allow?