Get Juniper JN0-664 Exam Practice Questions - Real and Updated

Answer : B, C

BGP route target filtering can be configured on PE devices or on route reflectors (RRs). Configuring BGP route target filtering on RRs is more efficient and scalable, as it reduces the number of BGP sessions and updates between PE devices. To configure BGP route target filtering on RRs, the following steps are required:

Configure the family route-target statement under the BGP group or neighbor configuration on the RRs. This enables the exchange of the route-target address family between the RRs and their clients (PE devices). Configure the resolution rib bgp.l3vpn.0 resolution-ribs inet.0 statement under the routing-options configuration on the RRs. This enables the RRs to resolve next hops for VPN routes using the inet.0 routing table.

Answer : A, B

The hello interval is the time interval between two consecutive hello packets sent by an OSPF router on an interface. The dead interval is the time interval after which a neighbor is declared down if no hello packets are received from it. These parameters must match between two OSPF routers for them to form an adjacency. In the exhibit, router R1 has a hello interval of 10 seconds and a dead interval of 40 seconds, while router R2 has a hello interval of 30 seconds and a dead interval of 120 seconds.This causes a mismatch and prevents them from becoming neighbors23.

Answer : B, C

Intermediate System to Intermediate System (IS-IS) is a link-state routing protocol that supports Level 1 (L1), Level 2 (L2), or both (L1/L2) operations. The way IS-IS sends Hello (IIH) packets depends on whether the interface is point-to-point (P2P) or broadcast (LAN).

Evaluating the Answer Choices

Option A: 'If a point-to-point interface is in both L1 and L2, separate hello messages are sent for each level.'

Incorrect!

On point-to-point (P2P) interfaces, only one combined Hello message is sent for both L1 and L2.

IS-IS P2P Hellos include both Level 1 and Level 2 TLVs in the same message.

This statement is incorrect.

Option B: 'If a point-to-point interface is in both L1 and L2, one combined hello message is sent for both levels.'

Correct!

On point-to-point (P2P) links, IS-IS sends a single Hello message that includes TLVs for both L1 and L2.

This reduces overhead and simplifies adjacency formation.

This statement is correct.

Option C: 'If a broadcast interface is in both L1 and L2, separate hello messages are sent for each level.'

Correct!

On broadcast (LAN) interfaces, IS-IS sends separate Hello messages for L1 and L2.

This is because L1 and L2 use separate Designated IS (DIS) elections and different multicast addresses:

L1 Hellos: Sent to AllL1IS (01:80:C2:00:00:14)

L2 Hellos: Sent to AllL2IS (01:80:C2:00:00:15)

This statement is correct.

Option D: 'If a broadcast interface is in both L1 and L2, one combined hello message is sent for both levels.'

Incorrect!

As stated above, IS-IS sends separate Hello messages for L1 and L2 on broadcast interfaces because they have independent DIS elections.

This statement is incorrect.

Final Answer:

B. If a point-to-point interface is in both L1 and L2, one combined hello message is sent for both levels. C. If a broadcast interface is in both L1 and L2, separate hello messages are sent for each level.

Verification from Juniper Documentation

Juniper IS-IS Configuration Guide confirms:

Point-to-Point (P2P) interfaces send one combined Hello for both levels.

Broadcast interfaces send separate L1 and L2 Hellos due to separate DIS elections.

RFC 1195 (IS-IS Extensions for IPv4) specifies that broadcast networks require distinct Hellos per level.

Answer : B

Answer : A, B, D

Intermediate System to Intermediate System (IS-IS) is a link-state routing protocol designed to move information efficiently within a computer network, a group of physically connected computers or similar devices. It operates in two levels, Level 1 (L1) and Level 2 (L2), and supports hierarchical routing within a multi-area network.

Let's analyze each statement to determine its correctness in the context of IS-IS multi-area networks.

1. **Statement A: Internal L1 PDUs are flooded to the local area's L2 routers.**

- This statement is correct. L1 PDUs (Protocol Data Units) are flooded within the L1 area and also to the L2 routers that are present in the same area. These L2 routers act as the boundary routers that connect the local L1 area to other L1 areas via L2.

2. **Statement B: External L2 PDUs are flooded to all L2 routers in other areas.**

- This statement is correct. L2 PDUs are flooded throughout the entire L2 backbone, which includes all L2 routers in different areas. This ensures that inter-area routing information is shared across the network.

3. **Statement C: Internal L1 PDUs are flooded to all L1 routers in other areas.**

- This statement is incorrect. Internal L1 PDUs are only flooded within the local L1 area. They do not cross L1 area boundaries; inter-area communication is handled by L2 routers.

4. **Statement D: Internal L1 PDUs are only flooded to the local area's L1 routers.**

- This statement is correct. Internal L1 PDUs are indeed only flooded within their local L1 area, and do not go beyond it.

5. **Statement E: External L2 PDUs are only flooded to the local area's L2 routers.**

- This statement is incorrect. External L2 PDUs are flooded to all L2 routers throughout the IS-IS network, not just to those in the local area. This allows L2 routers to maintain a complete map of the network's topology.

**Conclusion**:

Given the analysis, the correct answers are:

**A. Internal L1 PDUs are flooded to the local area's L2 routers.**

**B. External L2 PDUs are flooded to all L2 routers in other areas.**

**D. Internal L1 PDUs are only flooded to the local area's L1 routers.**

**Reference**:

- Juniper Networks Documentation on IS-IS: [IS-IS Overview](https://www.juniper.net/documentation/en_US/junos/topics/concept/is-is-routing-overview.html)

- RFC 1195, Use of OSI IS-IS for Routing in TCP/IP and Dual Environments: [RFC 1195](https://tools.ietf.org/html/rfc1195) which details the operation of IS-IS in multi-area networks.