Free Practice Questions for Nokia 4A0-114 Exam

IPv6 Link-Local addresses are specific types of addresses used within a single local network segment. Here are key points about IPv6 Link-Local addresses:

A. True: Every physical interface running IPv6 is assigned a Link-Local address automatically.

B. True: Link-Local addresses are only valid for communication within the same broadcast domain (i.e., the local link).

C. True: They all have the same 64-bit subnet prefix (FE80::/64).

The false statement is:

D. False: The interface ID for Link-Local addresses is not derived from the interface’s IPv4 address. Instead, it is typically generated from the interface’s MAC address or using a random number.

ReferencesNokia Border Gateway Protocol Fundamentals, Chapter on IPv6 Addressing.

BGP Peer Discovery: Unlike some other routing protocols (e.g., OSPF, EIGRP), BGP does not use Hello messages to discover peers dynamically. Instead, BGP peers (neighbors) must be manually configured.

TCP Session: For BGP to operate, it requires an underlying TCP connection (port 179) between the two routers.

OPEN Message: The initial BGP message sent after establishing the TCP connection is the OPEN message, which is used to negotiate session parameters and exchange capabilities.

Exterior Routing Protocol: BGP was designed primarily for inter-AS (Autonomous System) routing, making it suitable for internet backbone routing and other exterior routing scenarios.

References:

Nokia BGP Fundamentals Documentation, Chapter on BGP Peer Establishment

RFC 4271 (A Border Gateway Protocol 4), Section 4

In the context of BGP confederations, each sub-AS within the confederation behaves like a regular AS, but the entire confederation acts as a single AS when seen from the outside.

The given network diagram shows routers R1, R2, and R3 as part of the same confederation with different sub-AS numbers.

Router R2 is part of sub-AS 65101.

Confederation configuration for Router R2 must reflect its sub-AS membership and its relationships with its peers within the same confederation and external peers.

Option C shows Router R2 belonging to sub-AS 65101 and appropriately configuring its peers within the confederation.

References

Nokia Border Gateway Protocol Fundamentals documentation

Standard BGP configuration practices for confederations as per Nokia's guidelines

When a TCP connection fails to be established with a BGP peer, the BGP state machine goes through several states. The initial state is "Idle". In this state, BGP initializes all resources and awaits a start event. After initiating a TCP connection to the peer, it transitions to the "Connect" state. If the TCP connection attempt is unsuccessful, the state will transition to "Active", where BGP will continue to try to establish the TCP connection.

Idle: BGP is waiting for a start event to initialize a connection.

Connect: BGP is trying to establish a TCP connection.

Active: BGP attempts to establish a connection if the previous TCP connection attempt fails.

Since the question specifies the failure of TCP connection establishment, the valid states are "Idle" and "Active".

ReferencesNokia Border Gateway Protocol Fundamentals, Chapter on BGP States and the BGP Finite State Machine.

Understanding the AS Path Traversal:

The question states that an update travels from AS 137000 to AS 135000, passing through both 32-bit and 16-bit AS Paths.

The Autonomous Systems (AS) involved in the diagram are AS 137000, AS 140000, AS 200 (16-bit), and AS 135000.

Analyzing the AS Path:

The update starts at AS 137000.

It then moves to AS 140000.

From AS 140000, it reaches AS 200 (which is a 16-bit AS).

Finally, it reaches AS 135000.

AS Path Seen by AS 200:

When the update reaches AS 200, the AS Path recorded will include all the Autonomous Systems it has traversed so far, in reverse order.

Therefore, the AS Path seen by AS 200 will include AS 137000 and AS 140000, in that order.

Verifying the Answer:

The AS Path seen by AS 200 should show the sequence of ASes the update has traversed before reaching AS 200.

Thus, the correct AS Path is: 137000 140000.

References

Nokia Border Gateway Protocol (BGP) Fundamentals documentation

BGP Path Attributes and AS Path documentation

Standard BGP routing behavior and AS Path recording principles

A distributed EVPN VPRN service acts as a router for IP packets between customer sites.

It does require two types of interfaces: one towards customer sites (CEs) and another towards the EVPN VPLS for backhaul connectivity.

The configured route target (RT) helps PE routers identify relevant BGP updates.

MP-BGP with the EVPN address family is used to populate the routing table.

Therefore, the statement "It requires two types of interfaces, one towards customer sites and one towards the backhaul VPLS." is FALSE because the backhaul VPLS reference should instead pertain to VPRN backhaul routing.

References:

Nokia Border Gateway Protocol Fundamentals documentation, Section 9.2 on EVPN VPRN interface requirements and configuration.

BGP Shortcuts Concept: BGP shortcuts leverage MPLS tunnels to carry transit traffic efficiently across the network, reducing the need for full-mesh iBGP peering.

Statement Analysis:

Option A: Correct. MPLS tunnels are indeed used to carry transit traffic across the network.

Option B: Correct. A full mesh of iBGP peering sessions is not required when using BGP shortcuts.

Option C: Incorrect. Only edge routers need to be configured with BGP. Transit routers only need to support MPLS (LDP or RSVP-TE) but do not need to run BGP.

Option D: Correct. Transit routers need to support LDP (Label Distribution Protocol) or RSVP-TE (Resource Reservation Protocol-Traffic Engineering) LSPs (Label Switched Paths).

Conclusion: Option C is false because transit routers do not need to be configured with BGP.

References:

Nokia Border Gateway Protocol Fundamentals

Nokia 7750 SR OS BGP Configuration Guide

Best Practices for BGP Address Planning:

Proper address planning ensures efficient and reliable BGP operations.

It involves using specific addresses for BGP sessions and advertising appropriate routes.

Analyzing the Options:

A. Advertising external networks into IGP: Not recommended as it can lead to IGP table bloating and instability.

B. Using system addresses for setting up iBGP sessions: This is considered a best practice. System addresses (loopback addresses) are stable and do not change even if the physical interface goes down, ensuring session stability.

C. Exporting the networks associated with the external links of eBGP peers into BGP: This is normal practice but not directly related to address planning best practices.

D. Optimizing BGP route table by exporting IGP routes into BGP: Typically, you would do the opposite (importing BGP routes into IGP selectively).

Conclusion:

Using system addresses (loopback addresses) for setting up iBGP sessions is a widely accepted best practice. It enhances the reliability and stability of the BGP sessions.

References

Nokia Border Gateway Protocol (BGP) Fundamentals documentation

Best practices in BGP design and implementation

Network stability and reliability considerations in BGP configurations

The AS_PATH attribute in BGP is classified as a well-known mandatory attribute. Well-known attributes are recognized by all BGP implementations, and mandatory attributes must be included in all BGP update messages. The AS_PATH attribute lists the autonomous systems that a route has traversed, which is essential for loop prevention and routing policy decisions.

Optional transitive: Attributes that are optional and passed along to other BGP peers.

Optional non-transitive: Attributes that are optional and not passed along.

Well-known discretionary: Attributes recognized by all BGP implementations but not necessarily included in all update messages.

Well-known mandatory: Attributes that must be included in every BGP update message.

ReferencesNokia Border Gateway Protocol Fundamentals, Chapter on BGP Path Attributes.