JN0-346 juniper

Transcription

1 JN0-346 juniper Number: JN0-346 Passing Score: 800 Time Limit: 120 min

2 Exam A QUESTION 1 Click the Exhibit button. Referring to the exhibit, what does the asterisk (*) indicate? A. The router received this entry. B. This entry is stale. C. This entry is new. D. The router originated this entry. Correct Answer: C /Reference: The asterisk (*) next to one of the block entries corresponds to the active route that is used for new traffic. The term 'new traffic' corresponds to a single packet or an entire flow to a destination, depending on the type of switching configured. References: QUESTION 2 What are three RSTP port states? (Choose three.). A. learning B. forwarding C. listening D. blocking E. discarding Correct Answer: ABE

3 /Reference: Port States in STP and RSTP References: QUESTION 3 Click the Exhibit button. Referring to the exhibit, which router will be selected as the DR? A. R1 B. R5 C. R4 D. R3 Correct Answer: D /Reference: Note: The higher the priority value, the greater likelihood the routing device will become the designated router. By default, routing devices have a priority of 128. A priority of 0 marks the routing device as ineligible to become the designated router. A priority of 1 means the routing device has the least chance of becoming a designated router. A priority of 255 means the routing device is always the designated router.

4 References: QUESTION 4 Click the Exhibit button. Referring to the exhibit, what does the asterisk (*) following the ge-0/0/5.0 interface indicate? A. It indicates the interface is a trunk port. B. It indicates the interface is not active. C. It indicates the interface is an access port. D. It indicates the interface is active. Correct Answer: D /Reference: An asterisk (*) beside the interface indicates that the interface is UP. References: show-vlans-bridging-qfx-series.html QUESTION 5

5 Click the Exhibit button. Referring to the exhibit, what is the problem? A. LAG requires more than two member links. B. LACP is required for LAG to work. C. Aggregated interfaces must be defined under the chassis stanza. D. The LAG member interfaces are configured across different line cards. Correct Answer: C /Reference: Use the link aggregation feature to aggregate one or more links to form a virtual link or link aggregation group (LAG). To configure aggregated Ethernet interfaces, using the CLI: 1. Specify the number of aggregated Ethernet interfaces to be created: [edit chassis] user@switch# set aggregated-devices ethernet device-count 2 2. Specify the minimum number of links for the aggregated Ethernet interface (aex), that is, the defined bundle, to be labeled up : [edit interfaces] user@switch# set ae0 aggregated-ether-options minimum-links 2

6 3. Specify the link speed for the aggregated Ethernet bundle: [edit interfaces] set ae0 aggregated-ether-options link-speed 10g 4. Specify the members to be included within the aggregated Ethernet bundle: [edit interfaces] set xe-0/1/0 ether-options 802.3ad ae0 set xe-1/1/0 ether-options 802.3ad ae0 5. Specify an interface family for the aggregated Ethernet bundle: [edit interfaces] set ae0 unit 0 family inet address /25 Incorrect Answers: A: Two member links is OK. B: For aggregated Ethernet interfaces on EX Series switches, you can configure the Link Aggregation Control Protocol (LACP). LACP is one method of bundling several physical interfaces to form one logical interface. You can configure aggregated Ethernet with or without LACP enabled. References: QUESTION 6 Which two statements about RSTP are correct? (Choose two.) A. RSTP is not backwards compatible with STP. B. RSTP is backwards compatible with STP. C. RSTP permits multiple root bridges within a Layer 2 domain. D. RSTP permits only a single root bridge within a Layer 2 domain. Correct Answer: BC /Reference: B: RSTP and STP can co-exist. RSTP achieves its rapid converges over STP through new mechanisms. If a RSTP switch connects to an STP switch, the RSTP switch will drop down to STP convergence speeds on a per-port basis. C: Unlike 802.1d (STP), 802.1w (RSTP) uses Hello packets between bridges to maintain link states and does not rely on the root bridge. References: QUESTION 7

7 Click the Exhibit button. A routing table contains multiple BGP routes to the same destination prefix. The route preference is the same for each route. Referring to the exhibit, which route would be selected? A. route A B. route D C. route B D. route C Correct Answer: C /Reference: Route B with the highest local preference is preferred. See step 3 below. Understanding BGP Path Selection The algorithm for determining the active route is as follows: 1. Verify that the next hop can be resolved. 2. Choose the path with the lowest preference value 3. Prefer the path with higher local preference. 4. If the accumulated interior gateway protocol (AIGP) attribute is enabled, prefer the path with the lower AIGP attribute. 5. Prefer the path with the shortest autonomous system (AS) path value (skipped if the as-path-ignore statement is configured). 6. Prefer the route with the lower origin code. 7. Prefer the path with the lowest multiple exit discriminator (MED) metric. References: QUESTION 8 Which two port security features are dependent on the DHCP snooping database? (Choose two.) A. MAC limiting B. dynamic ARP inspection C. IP source guard D. storm control Correct Answer: BC /Reference: B: Dynamic ARP inspection (DAI) prevents Address Resolution Protocol (ARP) spoofing attacks. ARP requests and replies are compared against entries in the DHCP snooping database, and filtering decisions are made on the basis of the results of those comparisons. C: IP source guard mitigates the effects of IP address spoofing attacks on the Ethernet LAN. With IP source guard enabled, the source IP address in the packet sent from an untrusted access interface is validated against the source MAC address in the DHCP snooping database. The packet is forwarded if the source IP- MAC binding is valid; if the binding is not valid, the packet is discarded. You enable IP source guard on a VLAN. EX Series switches support IPv6 source guard also.

8 References: QUESTION 9 How many bytes of overhead does an IP-IP tunnel add to a packet? A. 24 bytes B. 28 bytes C. 20 bytes D. 14 bytes Correct Answer: C /Reference: Difference Between GRE and IP-IP Tunnel. Generic Routing Encapsulation (GRE) and IP-in-IP (IPIP) are two rather similar tunneling mechanisms which are often confused. In terms of less overhead, the GRE header is 24 bytes and an IP header is 20 bytes. References: QUESTION 10 Click the Exhibit button. Referring to the exhibit, which two statements are true? A. The policya routing policy takes precedence over all other policies. B. No policy is used for neighbor C. The policyb routing policy is used by neighbor D. The policyd routing policy is the only policy used by neighbor Correct Answer: CD

9 /Reference: C: A group-level import or export statement, such as export policyb within the group ibgp-peers statements, overrides a global BGP import or export statement. It is applied to neighbor Incorrect Answers: A: A group-level import or export statement overrides a global BGP import or export statement. References: QUESTION 11 Click the Exhibit button. Referring to the exhibit, you are asked to ensure that host-1 can communicate with host-3 while also allowing host-2 to communicate with host-4. What should you do to enable this behavior? A. Configure the native-vlan-id default statement under the ge-0/0/1 port settings on Switch-1. B. Use the all keyword when defining the member VLANs for the ge-0/0/1 interface on Switch-1. C. Configure the native-vlan-id default statement under the ge-0/0/1 port settings on both Switch-1 and Switch-2. D. Use the all keyword when defining the member VLANs for the ge-0/0/1 interface on both Switch-1 and Switch-2. Correct Answer: C /Reference: Configuring Mixed Tagging Support for Untagged Packets For 1-, 4-, and 8-port Gigabit Ethernet IQ2 and IQ2-E PICs, for 1-port 10-Gigabit Ethernet IQ2 and IQ2-E PICs, for all MX Series router Gigabit Ethernet, Tri-Rate Ethernet copper, and 10-Gigabit Ethernet interfaces configured for 802.1Q flexible VLAN tagging, and for aggregated Ethernet interfaces on IQ2 and IQ2-E PICs or MX Series DPCs, you can configure mixed tagging support for untagged packets on a port. Untagged packets are accepted on the same mixed VLAN-tagged port. To accept untagged packets, include the native-vlan-id statement and the flexible-vlan-tagging statement at the [edit interfaces interface-name] hierarchy level: [edit interfaces ge-fpc/pic/port] flexible-vlan-tagging; native-vlan-id number; References: QUESTION 12

10 Click to the exhibit button. Referring to the exhibit, which configuration change is needed for an IS-IS Level 1 adjacency between R1 and R2? A. Configure the Io0 family ISO address on R1. B. Disable Level 2 on R2 s ge-0/0/1 interface. C. Configure the Io0 family ISO address on R2. D. Enable Level 2 on R1 s ge-0/0/1 interface. Correct Answer: C /Reference: Level 1 adjacencies can be formed between routers that share a common area number. We need to change ISO addresses so that both routers have the same area number. If we change the ISO address on R , both routers will have 0002 as area number. Note: Level 2 adjacency can be formed between routers that might or might not share an area number. References: QUESTION 13 Which two statements are correct about redundant trunk groups on EX Series switches? (Choose two.) A. Layer 2 control traffic is permitted on the secondary link. B. If the active link fails, then the secondary link automatically takes over. C. Redundant trunk groups load balance traffic across two designated uplink interfaces. D. Redundant trunk groups use spanning tree to provide loop-free redundant uplinks.

11 Correct Answer: AB /Reference: A: While data traffic is blocked on the secondary link, Layer 2 control traffic is still permitted. For example, an LLDP session can be run between two switches on the secondary link. B: The redundant trunk group is configured on the access switch and contains two links: a primary or active link, and a secondary link. If the active link fails, the secondary link automatically starts forwarding data traffic without waiting for normal spanning-tree protocol convergence. References: QUESTION 14 Click the Exhibit button. Referring to the exhibit, which statement is correct? A. This device is the root bridge. B. The spanning tree session has timed out. C. The bridge priority on the root device is set to 8k. D. The local bridge priority is set to 8k. Correct Answer: C /Reference: The Root ID field is the Bridge ID of the elected spanning tree root bridge. The bridge ID consists of a

12 configurable bridge priority and the MAC address of the bridge. Here the bridige priority is 8192, which is 8k. Incorrect Answers: A: The Root cost field is the calculated cost to reach the root bridge from the bridge where the command is entered. Here it is B: As the Message age is only 4 and Maximum age is 40, the session has not timed out. D: The bridge priority, not the local bridge priority, is set to 8k. References: show-spanning-tree-bridge-spanning-trees-ex-series.html QUESTION 15 Click to the Exhibit button. Referring to the exhibit, which router will become the BDR if all routers are powered on at the same time? A. R3 B. R2 C. R1 D. R4 Correct Answer: A /Reference: In LANs, the election of the designated router takes place when the OSPF network is initially established. When the first OSPF links are active, the routing device with the highest router identifier (defined by the router-id configuration value, which is typically the IP address of the routing device, or the loopback address) is elected the designated router. The routing device with the second highest router identifier is elected the backup designated router. References:

13 QUESTION 16 Click the Exhibit button. Switch-1 in the exhibit receives a packet from User A with a destination MAC address of 00:26:88:02:74:48. Which statement is correct? A. Switch-1 floods the packet out ge-0/0/6, ge-0/0/7, and ge-0/0/8. B. Switch-1 sends the packet out ge-0/0/7 only. C. Switch-1 sends the packet out ge-0/0/8 only. D. Switch-1 floods the packet out ge-0/0/7 and ge-0/0/8. Correct Answer: D /Reference: A switch populates its mac-address table with mac addresses registered on incoming frames. As a result, when the switch needs to forward a frame destined to that specific mac-address, it will know out of which port to send the frame. Flooding however occurs when the switch does not know of the destination mac-address say the switch has not learnt that mac address yet; or maybe that specific entry expired so it got flushed away from the mac-address table. To ensure the frame reaches its intended destination, the switch will replicate that frame out of all ports, less the port where the frame was received that s flooding. References: QUESTION 17

14 Switch-1 in the exhibit receives a packet from User A with a destination MAC address of 00:26:88:02:74:47. Which statement is correct in this scenario? A. Switch-1 floods the packet out ge-0/0/6, ge-0/0/7, ge-0/0/8, and ge-0/0/9. B. Switch-1 floods the packet out ge-0/0/7 and ge-0/0/8. C. Switch-1 floods the packet out ge-0/0/7, ge-0/0/8, and ge-0/0/9. D. Switch-1 sends the packet out ge-0/0/7 only. Correct Answer: C /Reference: To forward a frame destined to that specific mac-address, it will know out of which port to send the frame. Flooding however occurs when the switch does not know of the destination mac-address say the switch has not learnt that mac address yet; or maybe that specific entry expired so it got flushed away from the mac-address table. To ensure the frame reaches its intended destination, the switch will replicate that frame out of all ports, less the port where the frame was received that s flooding. References: QUESTION 18 An OSPF hello packet has been sent, but bidirectional communication has not been established. What is the state of the OSPF adjacency? A. Down B. Init C.Exchange D.Loading Correct Answer: A /Reference: Down is the first OSPF neighbor state. It means that no information (hellos) has been received from this neighbor, but hello packets can still be sent to the neighbor in this state. Incorrect Asnwers: B: The Init state specifies that the router has received a hello packet from its neighbor, but the receiving

15 router's ID was not included in the hello packet. References: QUESTION 19 What information is included in the DHCP snooping database? (Choose two.) A. client MAC address B. DHCP server address C. DHCP options D. VLAN Correct Answer: AD /Reference: When DHCP snooping is enabled, the lease information from the server is used to create the DHCP snooping table, also known as the binding table. The table shows current IP-MAC bindings, as well as lease time, type of binding, names of associated VLANs, and associated interface. References: QUESTION 20 Which three statements are correct about the voice VLAN feature? (Choose three.) A. It allows the access port to accept tagged voice and untagged data packets. B. It allows you to apply independent CoS actions to data and voice packets. C. It can be used with LLDP-MED to dynamically assign the VLAN ID value to IP phones. D. It allows trunk ports to accept tagged voice and untagged data packets. E. It must use the same VLAN ID as data traffic on a defined interface. Correct Answer: ABC /Reference: A (not D): 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 VLANs. B: To assign differentiated priority to Voice traffic, it is recommended that class of service (CoS) is configured prior to enabling the voice VLAN feature. Typically, voice traffic is treated with a higher priority than common user traffic. Without differentiated treatment through CoS, all traffic, regardless of the type, is subject to the same delay during times of congestion. C: In conjunction with Voice VLAN, you can utilize Link Layer Discovery Protocol Media Endpoint Discovery (LLDP-MED) to provide the voice VLAN ID and 802.1p values to the attached IP phones. This dynamic method associates each IP phone with the appropriate voice VLAN and assigns the necessary 802.1p values, which are used by CoS, to differentiate service for voice traffic within a network. References: QUESTION 21 Which two statements are correct about aggregate routes in the Junos OS? (Choose two.) A. An active route can contribute only to a single aggregate route. B. Only one aggregate route can be configured for each destination prefix. C. An aggregate route has a default next hop of an IP address. D. An aggregate route always shows as active in the routing table. Correct Answer: AB

16 /Reference: A route can contribute only to a single aggregate route. You can configure only one aggregate route for each destination prefix. Incorrect Answers: C: By default, when aggregate routes are installed in the routing table, the next hop is configured as a reject route. That is, the packet is rejected and an ICMP unreachable message is sent to the packet s originator. D: An aggregate route becomes active when it has one or more contributing routes. References: QUESTION 22 Which state indicates that the BGP session is fully converged? A. Connect B. Up C.Established D.Active Correct Answer: C /Reference: In order to make decisions in its operations with peers, a BGP peer uses a simple finite state machine (FSM) that consists of six states: Idle; Connect; Active; OpenSent; OpenConfirm; and Established. In the Established state, the peers send Update messages to exchange information about each route being advertised to the BGP peer. Incorrect Answers: A. In the connect state it waits for successful TCP negotiation with peer. B: There is no state named Up. D: If the router was unable to establish a successful TCP session, then it ends up in the Active state. References: QUESTION 23 Which static route next-hop value indicates that the packet will be silently dropped? A. resolve B. discard C. reject D. next-table Correct Answer: B /Reference: If the static route has a discard next hop it means that if a packet does not match a more specific route, the packet is rejected and a reject route for this destination is installed in the routing table, but Internet Control Message Protocol (ICMP) unreachable messages are not sent.

17 References: QUESTION 24 Which two prefixes are martian routes by default? (Choose two.) A /16 B /8 C /16 D /24 Correct Answer: BD /Reference: Martian addresses are host or network addresses about which all routing information is ignored. When received by the routing device, these routes are ignored. They commonly are sent by improperly configured systems on the network and have destination addresses that are obviously invalid. To view the default and configured martian routes, run the show route martians command. IPv4 Martian Addresses show route martians table inet. inet.0: /0 exact -- allowed /8 orlonger -- disallowed /8 orlonger -- disallowed /24 orlonger -- disallowed /4 orlonger -- disallowed /4 exact -- disallowed /24 exact -- disallowed inet.1: Etc /0 exact -- allowed /8 orlonger -- disallowed /8 orlonger -- disallowed /24 orlonger -- disallowed /4 orlonger -- disallowed References: QUESTION 25 You configured a GRE tunnel that traverses a path using default MTU settings. You want to ensure that packets are not dropped or fragmented. In this scenario, what is the maximum packet size that would traverse the GRE tunnel? A B C D Correct Answer: A /Reference: The default Ethernet MTU is There is a 24 byte GRE overhead, so there remain 1476 bytes for the data packet. References:

18 QUESTION 26 Which two statements are true about a unified ISSU? (Choose two.) A. It requires that Bidirectional Forwarding Detection be disabled. B. It is only supported on platforms with redundant control planes. C. It is only supported on platforms with redundant power supplies. D. It requires that graceful Routing Engine switchover be enabled. Correct Answer: BD /Reference: B: Recent development work by many router vendors has focused on an effort to provide hitless control plane switchovers, which means keeping the control plane states in sync between the active and standby control planes prior to a switchover. Many consider this capability to be a prerequisite to delivering ISSU. Hitless control plane switchovers are usually implemented using the same version of code on both active and standby control plane components. However, ISSU design additionally requires different software versions running on active and standby control plane components. D: Unified ISSU is supported only on dual Routing Engine platforms. In addition, the graceful Routing Engine switchover (GRES) and nonstop active routing (NSR) must be enabled. References: QUESTION 27 What is the default route preference for BGP? A. 167 B. 170 C. 150 D. 179 Correct Answer: B /Reference: BGP has the default preference of 170. References: QUESTION 28

19 Click the Exhibit button. Your router is configured to peer with your ISP s router using BGP. You can only control your BGP configuration. Which address families are negotiated between the two BGP peers shown in the exhibit? A. inet-vpn-unicast B. inet-unicast inet-vpn-unicast 12vpn C.inet-unicast inet-vpn-unicast 12vpn-signaling D.inet-unicast Correct Answer: D /Reference: From the exhibit we see: NLRI for restart configured on peer: inet-unicast inet-vpn-unicast 12vpn But we also see: NLRI that restat is negotiaded for: inet-unicast NLRI of received end-of-rib markers: inet-unicast NLRI of all end-of-rib markers sent: inet-unicast

20 QUESTION 29 What is reviewed first in the BGP route selection process? A. the peer with the lowest IP address B. the route with an origin of incomplete C. the path with no MED value D. the next-hop resolution Correct Answer: D /Reference: Understanding BGP Path Selection The algorithm for determining the active route is as follows: 1. Verify that the next hop can be resolved. 2. Choose the path with the lowest preference value (routing protocol process preference). 3. Prefer the path with higher local preference. Etc. References: QUESTION 30 Click the Exhibit button. Referring to the exhibit, which type of route is displayed? A. static B. generate C. aggregate D. martian Correct Answer: C

21 /Reference: From the exhibit we see: /8 *[Aggegate/130] QUESTION 31 Click the Exhibit button. Referring to the exhibit, which type of route is displayed? A. generate B. martian C. aggregate D. static Correct Answer: C

22 /Reference: From the exhibit se see: Contributing Routes Note: Route aggregation allows you to combine groups of routes with common addresses into a single entry in the routing table. This decreases the size of the routing table as well as the number of route advertisements sent by the routing device. An aggregate route becomes active when it has one or more contributing routes. A contributing route is an active route that is a more specific match for the aggregate destination. References: QUESTION 32

23 Click the Exhibit button. Based on the traceoptions output shown in the exhibit, what is the problem with the adjacency? A. connectivity B. authentication mismatch C. area mismatch D. MTU mismatch

24 Correct Answer: C /Reference: From the exhibit we see: OSPF packet ignored: area mismatch QUESTION 33 Click the Exhibit button. Based on the output shown in the exhibit, which statement is correct? A. The ge-0/0/9 interface is using the default priority value. B. The ge-0/0/15 interface is using the default port cost. C. This switch has a bridge priority of 32k. D. This switch has been elected as the root bridge. Correct Answer: B /Reference: The default port cost for a 100 Mbit/s interface is 200,000, which is the port cost of the ge-0/0/15 interface. Note: Data rate and default STP path cost

25 Incorrect Answers: A: The default STP priority is (32k), but here the bridge priority is 8192 (8k). C: The switch has bridge priority of 8192, that is 8k. D: The Port Role: MSTP or RSTP port role. Designated (DESG), backup (BKUP), alternate (ALT), or root. Here it designated, not root. References: QUESTION 34 Click the Exhibit button. In the exhibit, each IP subnet in the network is associated with a unique VLAN ID. Which action will ensure that Host C will communicate with Host A and Host B? A. Configure all switch ports connecting to the host devices as access ports associated with a common VLAN. B. Configure an IRB interface for each VLAN and associate it with its corresponding VLAN. C. Configure all switch ports connecting to the host devices as trunk ports associated with all VLANs. D. Configure a port-based ACL that permits inter-vlan routing for all configured VLANs. Correct Answer: B /Reference: Configuring Routing Between VLANs on One Switch To segment traffic on a LAN into separate broadcast domains, you create separate virtual LANs (VLANs). Of course, you also want to allow these employees to communicate with people and resources in other VLANs. To forward packets between VLANs you normally you need a router that connects the VLANs. However, you can accomplish this on a Juniper Networks switch without using a router by configuring an integrated routing and bridging (IRB) interface (also known as a routed VLAN interface or RVI in versions of Junos OS that do not support Enhanced Layer 2 Software). References:

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