SP Network Infrastructure and Protocols 2 — Questions and Answers
Question 1: What technology allows service providers to create isolated virtual networks over shared physical infrastructure?
- STP
- VLANs (Correct answer)
- PAT
- ARP
Correct answer: VLANs
Virtual Local Area Networks (VLANs) logically segment a shared physical network so different customers or departments operate in isolated broadcast domains.
Question 2: In an MPLS VPN architecture, what is a Route Distinguisher (RD) used for?
- Encrypt customer routing tables
- Make overlapping customer IP addresses unique in the provider's VRF table (Correct answer)
- Define QoS policies per customer
- Identify the physical port on a PE router
Correct answer: Make overlapping customer IP addresses unique in the provider's VRF table
A Route Distinguisher prepends a unique value to customer IP prefixes so that overlapping addresses from different customers remain distinct in the provider's global routing table.
Question 3: Which monitoring protocol do service providers use to collect metrics from network devices like routers and switches?
- FTP
- SNMP (Correct answer)
- Telnet
- SMTP
Correct answer: SNMP
Simple Network Management Protocol (SNMP) is used to poll network devices for performance metrics, interface statistics, and fault notifications (traps).
Question 4: What is the purpose of Bidirectional Forwarding Detection (BFD) in service provider networks?
- Encrypt tunnel traffic between PE routers
- Rapidly detect link or path failures between network nodes (Correct answer)
- Assign MPLS labels to packets
- Balance traffic across multiple ISP uplinks
Correct answer: Rapidly detect link or path failures between network nodes
BFD provides fast failure detection by exchanging control packets at millisecond intervals, allowing routing protocols to converge much faster than native timers.
Question 5: A service provider uses RADIUS for what primary function?
- Routing protocol updates
- Authentication, Authorization, and Accounting for network access (Correct answer)
- Resolving domain names to IP addresses
- Distributing MPLS labels
Correct answer: Authentication, Authorization, and Accounting for network access
RADIUS (Remote Authentication Dial-In User Service) provides centralized AAA services, verifying user credentials and logging session data for billing and audit.
Question 6: What does 'network convergence' mean in the context of service provider routing?
- Combining multiple ISP connections into one
- The time it takes all routers to update their tables after a topology change (Correct answer)
- Encrypting all routing protocol messages
- Scaling bandwidth dynamically with traffic demand
Correct answer: The time it takes all routers to update their tables after a topology change
Network convergence is the process by which all routers in a network reach a consistent view of the topology after a change such as a link failure.
SP Network Infrastructure and Protocols 2
What technology allows service providers to create isolated virtual networks over shared physical infrastructure?