Juniper JN0-351 Practice Test - Questions Answers, Page 2

Option A suggests that the MTU is not at least 1492 bytes.This is correct because IS-IS requires a minimum MTU of 1492 bytes to establish adjacencies1.If the MTU is less than this, IS-IS adjacencies will not be established1.

Option D suggests that the lo0 interface is not included as an IS-IS interface.This is also correct because the loopback interface (lo0) is typically used as the router ID in IS-IS1.If the loopback interface is not included in IS-IS, it could prevent IS-IS adjacencies from being established1.

Therefore, options A and D are correct.

A firewall filter is a configuration that defines the rules that determine whether to forward or discard packets at specific processing points in the packet flow. A firewall filter can also modify the attributes of the packets, such as priority, marking, or logging.A firewall filter can be applied to various interfaces, protocols, or routing instances on a Juniper device1.

A firewall filter has a family attribute, which specifies the type of traffic that the filter can evaluate.The family attribute can be one of the following: inet, inet6, mpls, vpls, iso, or ethernet-switching2. The family inet firewall filter is used to evaluate IPv4 traffic, which is the most common type of Layer 3 traffic on a network.

To create a family inet firewall filter, you need to specify the appropriate match criteria and actions for each term in the filter. The match criteria can include various fields in the IPv4 header, such as source address, destination address, protocol, port number, or DSCP value.The actions can include accept, discard, reject, count, log, policer, or next term3.

To apply a firewall filter to Layer 3 traffic that is being sent between VLANs, you need to apply the filter to the appropriate IRB interface. An IRB interface is an integrated routing and bridging interface that provides Layer 3 functionality for a VLAN on a Juniper device. An IRB interface has an IP address that acts as the default gateway for the hosts in the VLAN.An IRB interface can also participate in routing protocols and forward packets to other VLANs or networks4.

Therefore, option C is correct, because you should create a family inet firewall filter with the appropriate match criteria and actions. Option D is correct, because you should apply the firewall filter to the appropriate IRB interface.

Option A is incorrect, because you should not create a family ethernet-switching firewall filter with the appropriate match criteria and actions. A family ethernet-switching firewall filter is used to evaluate Layer 2 traffic on a Juniper device.A family ethernet-switching firewall filter can only match on MAC addresses or VLAN IDs, not on IP addresses or protocols5.

Option B is incorrect, because you should not apply the firewall filter to the appropriate VLAN. A VLAN is a logical grouping of hosts that share the same broadcast domain on a Layer 2 network. A VLAN does not have an IP address or routing capability.A firewall filter cannot be applied directly to a VLAN; it must be applied to an interface that belongs to or connects to the VLAN6.

1:Firewall Filters Overview2:Configuring Firewall Filters3:Configuring Firewall Filter Match Conditions and Actions4:Understanding Integrated Routing and Bridging Interfaces5: Configuring Ethernet-Switching Firewall Filters6: Understanding VLANs

A keepalive OAM probe is a mechanism that can be used to monitor the state of a GRE tunnel and detect any failures in the tunnel path. A keepalive OAM probe consists of sending periodic packets from one end of the tunnel to the other and expecting a reply.If no reply is received within a specified time, the tunnel is considered down and the line protocol of the tunnel interface is changed to down1.

To configure a keepalive OAM probe for a GRE tunnel, you need to specify two parameters: the keepalive-time and the hold-time. The keepalive-time is the interval between each keepalive packet sent by the local router.The hold-time is the maximum time that the local router waits for a reply from the remote router before declaring the tunnel down2.

According to the Juniper Networks documentation, the hold-time value must be two times the keepalive-time value for a GRE tunnel2. This is because the hold-time value must account for both the round-trip time of the keepalive packet and the processing time of the remote router. If the hold-time value is too small, it may cause false positives and unnecessary tunnel flaps.

In the exhibit, the configuration shows that the keepalive-time is set to 10 seconds and the hold-time is set to 15 seconds for the gr-1/1/10.1 interface. This means that the local router will send a keepalive packet every 10 seconds and will wait for 15 seconds for a reply from the remote router. However, this hold-time value is not two times the keepalive-time value, which violates the recommended configuration. This may cause traffic drops if the remote router takes longer than 15 seconds to reply.

Therefore, option D is correct, because the hold-time value must be two times the keepalive-time value for a GRE tunnel.Option A is incorrect, because BFD is not required for GRE tunnels; BFD is another protocol that can be used to monitor tunnels, but it is not compatible with GRE keepalives3.Option B is incorrect, because the ''event link-adjacency-loss'' option is not related to GRE tunnels; it is an option that can be used to trigger an action when a link goes down4.Option C is incorrect, because LLDP does not need to be removed from the gr-1/1/10.1 interface; LLDP is a protocol that can be used to discover neighboring devices and their capabilities, but it does not interfere with GRE tunnels5.

1:Configuring Keepalive Time and Hold time for a GRE Tunnel Interface2: keepalive | Junos OS | Juniper Networks3: Configuring Bidirectional Forwarding Detection4: event link-adjacency-loss | Junos OS | Juniper Networks5: Understanding Link Layer Discovery Protocol

Option B suggests that the BGP session is not established. This is correct because in the output, the state of the BGP session is shown as ''Idle''.In BGP, an ''Idle'' state means that the BGP session is not currently established1.

Option C suggests that R1 is configured for AS 65400.This is also correct because in the output, it's shown that the local AS number is 654001.The local AS number represents the Autonomous System (AS) number of the router on which you're checking the BGP session1.

The maximum allowable MTU size for a default GRE tunnel without IPv4 traffic fragmentation is1476 bytes1.This is because GRE packets are formed by the addition of the original packets and the required GRE headers1.These headers are 24-bytes in length and since these headers are added to the original frame, depending on the original size of the packet we may run into IP MTU problems1.The most common IP MTU is 1500-bytes in length (Ethernet)1.When the tunnel is created, it deducts the 24-bytes it needs to encapsulate the passenger protocols and that is the IP MTU it will use1.For example, if we are forming a tunnel over FastEthernet (IP MTU 1500) the IOS calculates the IP MTU on the tunnel as: 1500-bytes from Ethernet - 24-bytes for the GRE encapsulation = 1476-Bytes1.

Ais correct because IBGP updates the next-hop attribute to ensure reachability within an AS. This is because the next-hop attribute is the IP address of the router that advertises the route to a BGP peer. If the next-hop attribute is not changed by IBGP, it would be the IP address of an external router, which may not be reachable by all routers within the AS.Therefore, IBGP updates the next-hop attribute to the IP address of the router that received the route from an EBGP peer1.

Bis correct because IBGP peers advertise routes received from EBGP peers to other IBGP peers. This is because BGP follows the rule of advertising only the best route to a destination, and EBGP routes have a higher preference than IBGP routes.Therefore, IBGP peers advertise routes learned from an EBGP peer to all BGP peers, including both EBGP and IBGP peers1.

In BGP, routing policies are used to control the flow of routing information between BGP peers1.

Option C suggests that import policies are applied after the RIB-In table.This is correct because import policies in BGP are applied to routes that are received from a BGP peer, before they are installed in the local BGP Routing Information Base (RIB-In)1.The RIB-In is a database that stores all the routes that are received from all peers1.

Option D suggests that export policies are applied after the RIB-Local table.This is correct because export policies in BGP are applied to routes that are being advertised to a BGP peer, after they have been selected from the local BGP Routing Information Base (RIB-Local)1.The RIB-Local is a database that stores all the routes that the local router is using1.

Therefore, options C and D are correct.

The feature that enables an interface on an EX Series switch to receive both untagged traffic (from the computer) and tagged traffic (from the IP phone) is thevoice VLAN12.

The voice VLAN feature in EX-series switches enables access ports to accept both data (untagged) and voice (tagged) traffic and separate that traffic into different VLANs12.This allows the switch to differentiate between voice and data traffic, ensuring that voice traffic can be treated with a higher priority12. Therefore, option D is correct.

The output shown in the exhibit is a brief display of the Ethernet switching table, which shows the learned Layer 2 MAC addresses for each VLAN and interface1.

The commandshow ethernet-switching tabledisplays the Ethernet switching table with brief information, such as the destination MAC address, the VLAN name, the forwarding state, and the interface name1.

The commandshow route forwarding-tabledisplays the routing table information for each protocol family, such as inet, inet6, mpls, iso, and so on2. It does not show the Ethernet switching table or the MAC addresses.

The commandshow ethernet-switching table extensivedisplays the Ethernet switching table with extensive information, such as the destination MAC address, the VLAN name, the forwarding state, the interface name, the VLAN index, and the tag type1. It shows more details than the brief output shown in the exhibit.

The commandshow route forwarding-table family ethernet-switchingdisplays the routing table information for the ethernet-switching protocol family, which shows the destination MAC address, the next-hop MAC address, and the interface name3. It does not show the VLAN name or the forwarding state.