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Question 61

Which protocol is commonly used to exchange VPNv6 routes between PE routers?

1. MP-BGP
2. LDP
3. BFD
4. OSPF

Correct Answer: 1

Explanation

Multiprotocol BGP (MP-BGP) is used to exchange VPN-specific routes, including VPNv6 routes, between Provider Edge routers. MP-BGP extends BGP to support multiple address families and can carry IPv6 VPN information across a service provider network. The VPNv6 address family allows providers to support separate customer IPv6 routing contexts while maintaining route isolation. LDP is primarily used for MPLS label distribution, BFD provides rapid failure detection, and OSPF is an IGP. Therefore, MP-BGP is the correct protocol for exchanging VPNv6 routes.

Question 62

Which MPLS VPN component determines which VPN routes are imported into a VRF?

1. Route Distinguisher
2. Route Target
3. AS_PATH
4. MPLS TTL

Correct Answer: 2

Explanation

Route Targets determine which VPN routes are imported into and exported from VRFs. When a PE router advertises a VPN route using MP-BGP, the route can contain one or more Route Target extended communities. The receiving VRF compares those values with its configured import policies. Matching routes are then considered for installation into that VRF. A Route Distinguisher serves a different purpose by making VPN routes unique. AS_PATH supports BGP path selection and loop prevention, while MPLS TTL controls packet lifetime. Therefore, Route Target is correct.

Question 63

What is the primary purpose of a Route Target export policy in an MPLS VPN?

1. To determine which VPN routes receive an RT when leaving a VRF
2. To assign an MPLS transport label
3. To calculate an OSPF metric
4. To authenticate a BGP session

Correct Answer: 1

Explanation

A Route Target export policy determines which Route Target extended community or communities are attached to routes when they are exported from a VRF into the provider’s VPN routing infrastructure. Remote PE routers can then use those RT values to determine whether the routes should be imported into particular customer VRFs. This mechanism allows service providers to control VPN connectivity between customer sites. Transport labels are handled by MPLS mechanisms, OSPF metrics belong to the IGP, and BGP authentication is a separate security function. Therefore, option 1 is correct.

Question 64

Which MPLS VPN identifier makes identical customer prefixes unique in the provider BGP table?

1. Route Target
2. Local Preference
3. Route Distinguisher
4. MED

Correct Answer: 3

Explanation

The Route Distinguisher (RD) makes otherwise identical customer prefixes unique in the provider’s VPNv4 or VPNv6 routing table. For example, two customers may both advertise 10.1.1.0/24. Different RDs allow these routes to be represented as separate VPN routes. The RD therefore provides uniqueness but does not determine which VRF imports the route. Route Targets control import and export policy, while Local Preference and MED are BGP path-selection attributes. Therefore, the Route Distinguisher is the correct answer.

Question 65

Which MPLS VPN routing table is typically associated with a specific customer on a PE router?

1. VRF
2. Global ARP table
3. MAC table
4. Default VLAN

Correct Answer: 1

Explanation

A Virtual Routing and Forwarding (VRF) instance provides an independent routing table for a customer or logical routing context on a PE router. In an MPLS Layer 3 VPN, customer-facing interfaces are associated with a VRF, and customer routes are maintained separately from the global routing table. This separation allows multiple customers to use overlapping address spaces without interfering with one another. The global ARP table, MAC table, and VLAN database do not provide the same Layer 3 routing isolation. Therefore, VRF is correct.

Question 66

Which BGP address family is used to carry IPv6 VPN routes?

1. VPNv4
2. IPv4 unicast
3. VPNv6
4. L2VPN only

Correct Answer: 3

Explanation

VPNv6 is the BGP address family used to carry IPv6 VPN routes in MPLS Layer 3 VPN architectures. Like VPNv4, VPNv6 combines customer addressing information with a Route Distinguisher so that overlapping address spaces can be supported across different VPNs. MP-BGP is used to distribute these routes between PE routers. VPNv4 is intended for IPv4 VPN routes, while IPv4 unicast is a different address family. L2VPN is associated with Layer 2 VPN services. Therefore, VPNv6 is correct.

Question 67

Which service provider technology is designed to carry IPv4 and IPv6 traffic across the same MPLS infrastructure?

1. MPLS
2. STP
3. LACP
4. VTP

Correct Answer: 1

Explanation

MPLS can transport different types of IP traffic across a service provider network by using labels and appropriate control-plane mechanisms. Service providers can use MPLS infrastructure to carry IPv4 and IPv6 services, including Layer 3 VPN services. MP-BGP can distribute VPN-specific IPv4 and IPv6 routes, while MPLS provides the transport mechanism through the provider core. STP is a Layer 2 loop-prevention protocol, LACP combines physical links, and VTP manages VLAN information in supported environments. Therefore, MPLS is the correct answer.

Question 68

Which protocol can be used to distribute IPv6 reachability information in an MPLS service provider core?

1. IS-IS
2. FTP
3. TFTP
4. SMTP

Correct Answer: 1

Explanation

IS-IS can distribute IPv6 reachability information through extensions that support IPv6 routing. This makes IS-IS suitable for dual-stack and IPv6 service provider environments. Service providers can use IS-IS as the underlying IGP while MPLS or Segment Routing provides the forwarding infrastructure. FTP and TFTP are file-transfer protocols, while SMTP is an email protocol. Therefore, IS-IS is a valid and commonly used routing protocol for IPv6 reachability in service provider networks.

Question 69

What does Segment Routing use to represent forwarding instructions or paths through the network?

1. Segments
2. VLANs
3. MAC addresses only
4. DNS records

Correct Answer: 1

Explanation

Segment Routing represents forwarding instructions using segments. A segment can identify a destination, an adjacency, or another supported network instruction. A packet can carry a sequence of segments that describes the desired forwarding behavior. In SR-MPLS, segments are represented using MPLS labels, while SRv6 uses IPv6 Segment Identifiers. This approach allows network operators to influence traffic paths while simplifying the control-plane signaling requirements associated with traditional traffic engineering. VLANs, MAC addresses, and DNS records do not represent Segment Routing instructions. Therefore, segments are correct.

Question 70

Which Segment Routing implementation uses IPv6 addresses as Segment Identifiers?

1. SR-MPLS
2. SRv6
3. LDP
4. RSVP-TE

Correct Answer: 2

Explanation

Segment Routing over IPv6, known as SRv6, uses IPv6 addresses called Segment Identifiers (SIDs) to represent instructions and destinations. These SIDs are carried within the IPv6 Segment Routing Header mechanism. SR-MPLS instead represents segments using MPLS labels. LDP distributes MPLS labels, while RSVP-TE is a signaling protocol historically used for MPLS traffic engineering. SRv6 provides a way to implement Segment Routing using the IPv6 data plane and can support both network and service-oriented instructions. Therefore, SRv6 is correct.

Question 71

Which technology allows an MPLS network to carry Ethernet services between customer sites?

1. Ethernet VPN
2. NTP
3. BFD
4. OSPF

Correct Answer: 1

Explanation

Ethernet VPN (EVPN) is a service provider technology that supports Ethernet connectivity across an IP/MPLS infrastructure. EVPN uses BGP as its control plane to advertise endpoint reachability information and can support various Layer 2 and Layer 3 services. It provides a scalable alternative to older approaches that relied heavily on data-plane MAC learning or point-to-point pseudowires. NTP is used for time synchronization, BFD for rapid failure detection, and OSPF for IP routing. Therefore, Ethernet VPN is the correct answer.

Question 72

Which EVPN route type advertises Ethernet Segment information?

1. Route Type 2
2. Route Type 3
3. Route Type 4
4. Route Type 5

Correct Answer: 3

Explanation

EVPN Route Type 4 is the Ethernet Segment route. It is used to advertise information about Ethernet Segments and plays an important role in multihoming scenarios. EVPN defines several route types for different control-plane functions. Route Type 2 advertises MAC/IP reachability, Route Type 3 is an Inclusive Multicast Ethernet Tag route, and Route Type 5 advertises IP prefixes. Understanding EVPN route types is important when troubleshooting BGP EVPN control-plane behavior. Therefore, Route Type 4 is the correct answer.

Question 73

Which EVPN route type is used for Inclusive Multicast Ethernet Tag information?

1. Route Type 1
2. Route Type 2
3. Route Type 3
4. Route Type 5

Correct Answer: 3

Explanation

EVPN Route Type 3 is the Inclusive Multicast Ethernet Tag (IMET) route. It is used to advertise information needed for handling BUM traffic, which includes Broadcast, Unknown Unicast, and Multicast traffic, across an EVPN service. EVPN uses different BGP route types for different control-plane functions. Route Type 1 is associated with Ethernet Auto-Discovery, Route Type 2 with MAC/IP Advertisement, Route Type 4 with Ethernet Segment information, and Route Type 5 with IP Prefix routes. Therefore, Route Type 3 is correct.

Question 74

Which traffic category includes Broadcast, Unknown Unicast, and Multicast traffic in an EVPN network?

1. BGP traffic
2. BUM traffic
3. TCP traffic
4. MPLS-only traffic

Correct Answer: 2

Explanation

BUM stands for Broadcast, Unknown Unicast, and Multicast. These traffic types require special handling in Ethernet VPN environments because they may need to be replicated or distributed to multiple endpoints. EVPN provides control-plane mechanisms and forwarding procedures to support BUM traffic efficiently across the provider network. BGP is the control-plane protocol used by EVPN, but it is not the name of this traffic category. TCP is a transport protocol. Therefore, BUM traffic is the correct answer.

Question 75

Which technology is commonly used to provide fast convergence when an MPLS service provider link fails?

1. BFD
2. FTP
3. DHCP
4. DNS

Correct Answer: 1

Explanation

BFD provides rapid detection of forwarding-path failures and can work with routing protocols to accelerate convergence. In a service provider network, quickly detecting a failed link can allow routing or label-switching mechanisms to remove the failed path and select an alternative. This can reduce traffic disruption compared with waiting for longer protocol timers. FTP and DHCP are application/network services unrelated to routing convergence, while DNS resolves names. Therefore, BFD is the appropriate technology for rapid failure detection.

Question 76

What is the main purpose of MPLS Fast Reroute (FRR)?

1. Provide a backup forwarding path quickly after a failure
2. Assign IPv4 addresses
3. Encrypt MPLS labels
4. Synchronize network clocks

Correct Answer: 1

Explanation

MPLS Fast Reroute (FRR) is designed to provide rapid local protection when a network failure occurs. Instead of waiting for the entire routing control plane to reconverge, traffic can be redirected through a pre-established backup path. This can significantly reduce packet loss and service disruption during failures. FRR is especially useful in service provider networks where availability and fast restoration are important. It does not assign IP addresses, encrypt MPLS labels, or synchronize clocks. Therefore, providing a backup forwarding path quickly after a failure is correct.

Question 77

Which type of MPLS Traffic Engineering protection provides a backup path around a failed link or node?

1. Fast Reroute
2. NAT
3. DHCP relay
4. DNS forwarding

Correct Answer: 1

Explanation

Fast Reroute (FRR) provides rapid protection against failures affecting an MPLS Traffic Engineering path. Depending on the design, a backup tunnel or local repair path can protect against a failed link or node. When a failure is detected, traffic can be redirected through the backup path without waiting for full network-wide convergence. This improves service availability and reduces interruption time. NAT, DHCP relay, and DNS forwarding have unrelated functions. Therefore, Fast Reroute is the correct protection mechanism.

Question 78

Which protocol is commonly used to monitor network devices and collect operational information from service provider infrastructure?

1. SNMP
2. LDP
3. RSVP
4. BGP

Correct Answer: 1

Explanation

Simple Network Management Protocol (SNMP) is commonly used to monitor network devices and collect operational information. Network management systems can use SNMP to retrieve counters, interface information, system statistics, and other management data. SNMP can also support notifications such as traps or informs. LDP distributes MPLS labels, RSVP can support signaling and traffic engineering, and BGP exchanges routing information. Although modern service providers increasingly use streaming telemetry and APIs, SNMP remains an important network-management technology. Therefore, SNMP is correct.

Question 79

Which SNMP message is typically sent by a network device without first receiving a request from the management system?

1. GET
2. SET
3. TRAP
4. GETNEXT

Correct Answer: 3

Explanation

An SNMP TRAP is an unsolicited notification sent by an SNMP agent to a management system. It can report events such as interface failures, threshold violations, or other conditions configured for notification. In contrast, GET and GETNEXT are request messages used by an SNMP manager to retrieve information, while SET is used to modify supported management values. Traps can provide event-driven notifications without requiring the management system to continuously poll for every event. Therefore, TRAP is the correct answer.

Question 80

Which technology is commonly used to synchronize precise time in applications requiring more accurate timing than traditional NTP?

1. PTP
2. FTP
3. TFTP
4. SMTP

Correct Answer: 1

Explanation

Precision Time Protocol (PTP), defined by IEEE 1588, provides highly accurate time synchronization and is used in environments where traditional NTP may not provide sufficient precision. Service provider networks can use precise timing for applications such as mobile networks, synchronization-sensitive services, and other systems with strict timing requirements. PTP can achieve significantly greater precision depending on the network architecture and hardware support. FTP and TFTP are file-transfer protocols, while SMTP is used for email transport. Therefore, PTP is the correct answer.