QUESTION: 5

Which statement is correct about graceful Routing Engine switchover (GRES)?

The PFE restarts and the kernel and interface information is lost.
GRES has a helper mode and a restarting mode.
When combined with NSR, routing is preserved and the new master RE does not restart rpd.
With no other high availability features enabled, routing is preserved and the new master RE does not restart rpd.

Answer(s): C

Explanation:

The Graceful Routing Engine Switchover (GRES) feature in Junos OS enables a router with redundant Routing Engines to continue forwarding packets, even if one Routing Engine fails1. GRES preserves interface and kernel information, ensuring that traffic is not interrupted1. However, GRES does not preserve the control plane1.
To preserve routing during a switchover, GRES must be combined with either Graceful Restart protocol extensions or Nonstop Active Routing (NSR)1.
When GRES is combined with NSR, nearly 75 percent of line rate worth of traffic per Packet Forwarding Engine remains uninterrupted during GRES1. Any updates to the primary Routing Engine are replicated to the backup Routing Engine as soon as they occur1.
Therefore, when GRES is combined with NSR, routing is preserved and the new master RE does not restart rpd1.

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QUESTION: 6

Which statement is correct about controlling the routes installed by a RIB group?

An import policy is applied to the RIB group.
Only routes in the last table are installed.
A firewall filter must be configured to install routes in the RIB groups.
An export policy is applied to the RIB group.

Answer(s): A

Explanation:

A RIB group is a configuration that allows a routing protocol to install routes into multiple routing tables in Junos OS. A RIB group consists of an import-rib statement, which specifies the source routing table, and an export-rib statement, which specifies the destination routing table or group. A

RIB group can also include an import-policy statement, which specifies one or more policies to control which routes are imported into the destination routing table or group1. An import policy is a policy statement that defines the criteria for accepting or rejecting routes from the source routing table. An import policy can also modify the attributes of the imported routes, such as preference, metric, or community. An import policy can be applied to a RIB group by using the import-policy statement under the [edit routing-options rib-groups] hierarchy level1. Therefore, option A is correct, because an import policy is applied to the RIB group to control which routes are installed in the destination routing table or group. Option B is incorrect, because all routes in the source routing table are imported into the destination routing table or group, unless filtered by an import policy. Option C is incorrect, because a firewall filter is not used to install routes in the RIB groups; a firewall filter is used to filter packets based on various criteria. Option D is incorrect, because an export policy is not applied to the RIB group; an export policy is applied to a routing protocol to control which routes are advertised to other devices.

Reference:

1: rib-groups | Junos OS | Juniper Networks

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QUESTION: 7

Exhibit.

You are using OSPF to advertise the subnets that are used by the Denver and Dallas offices. The routers that are directly connected to the Dallas and Denver subnets are not advertising the connected subnets.
Referring to the exhibit, which two statements are correct? (Choose two.)

Create static routes on the switches using the local vMX router's loopback interface for the next hop.
Configure and apply a routing policy that redistributes the Dallas and Denver subnets using Type 5 LSAs.
Configure and apply a routing policy that redistributes the connected Dallas and Denver subnets.
Enable the passive option on the OSPF interfaces that are connected to the Dallas and Denver subnets.

Answer(s): C,D

Explanation:

The routers that are directly connected to the Dallas and Denver subnets are not advertising the connected subnets. This can be resolved by redistributing the connected subnets into OSPF1. Option C suggests to configure and apply a routing policy that redistributes the connected Dallas and Denver subnets. This is correct because redistribution allows routes from one routing protocol to be communicated to another, and in this case, it allows the connected subnets to be advertised through OSPF1.
Option D suggests enabling the passive option on the OSPF interfaces that are connected to the Dallas and Denver subnets. This is also correct because in OSPF, a passive interface is an interface that belongs to the OSPF router, but does not send OSPF Hello packets1. It's typically used on an interface that you don't want to use for OSPF adjacencies, but you still want to advertise its IP address1. Therefore, enabling passive interface can help in advertising the Dallas and Denver subnets.

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QUESTION: 8

Exhibit.

You want to verify prefix information being sent from 10.36.1.4.
Which two statements are correct about the output shown in the exhibit? (Choose two.)

The routes displayed have traversed one or more autonomous systems.
The output shows routes that were received prior to the application of any BGP import policies.
The output shows routes that are active and rejected by an import policy.
The routes displayed are being learned from an I BGP peer.

Answer(s): A,B

Explanation:

The output shown in the exhibit is the result of the command "show ip bgp neighbor 10.36.1.4 received-routes", which displays all received routes (both accepted and rejected) from the specified neighbor.
Option A is correct, because the routes displayed have traversed one or more autonomous systems. This can be seen from the AS_PATH attribute, which shows the sequence of AS numbers that the route has passed through. For example, the route 10.0.0.0/8 has an AS_PATH of 65001 65002, which means that it has traversed AS 65001 and AS 65002 before reaching the local router. Option B is correct, because the output shows routes that were received prior to the application of any BGP import policies. This can be seen from the fact that some routes have a status code of "r", which means that they are rejected by an import policy. The "received-routes" keyword shows the routes coming from a given neighbor before the inbound policy has been applied. To see the routes after the inbound policy has been applied, the "routes" keyword should be used instead. Option C is incorrect, because the output does not show routes that are active and rejected by an import policy. The status code of "r" means that the route is rejected by an import policy, but it does not mean that it is active. The status code of ">" means that the route is active and selected as the best path. None of the routes in the output have both ">" and "r" status codes. Option D is incorrect, because the routes displayed are not being learned from an IBGP peer. An IBGP peer is a BGP neighbor that belongs to the same AS as the local router. The output shows that the neighbor 10.36.1.4 has a remote AS of 65001, which is different from the local AS of 65002. Therefore, the neighbor is an EBGP peer, not an IBGP peer.

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