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NEW QUESTION # 75
Which statement is correct about an IP fabric?
- A. Load sharing is provided by the routing protocol used.
- B. The entire IP fabric is one large broadcast domain.
- C. Transit traffic is passed through the network based on the original frame's destination MAC address.
- D. Loop prevention is provided by the underlying spanning tree protocol used.
Answer: A
NEW QUESTION # 76
You are creating an IP fabric underlay and want to use OSPF as your routing protocol.
In this scenario, which statement is correct?
- A. Interface speeds should be the same throughout the fabric to ensure that all links are utilized.
- B. All leaf devices must be configured in separate OSPF areas.
- C. All leaf and spine devices must be the same model to ensure the proper load-balancing behavior.
- D. All spine devices must use the same router I
Answer: A
Explanation:
When creating an IP fabric underlay using OSPF as the routing protocol, consistent interface speeds are important to ensure optimal traffic distribution and utilization of all links. Step-by-Step Breakdown:
OSPF and Interface Speeds:
OSPF calculates the cost of a link based on its bandwidth.
The default cost calculation in OSPF is:
If interface speeds vary significantly, OSPF may choose paths with lower cost (higher bandwidth), resulting in some links being underutilized.
Equal Utilization:
To ensure that all links are equally utilized in an IP fabric, it is recommended to maintain uniform interface speeds across the fabric. This ensures balanced load sharing across all available paths. Juniper Reference: IP Fabric with OSPF: Juniper recommends consistent interface speeds to maintain even traffic distribution and optimal link utilization in IP fabric underlay designs.
NEW QUESTION # 77
When troubleshooting issues with static routes, what is a key factor to check first?
- A. The speed of the router's CPU
- B. If the routing table has enough memory
- C. The number of aggregate routes configured
- D. The correctness of the specified next-hop addresses
Answer: D
NEW QUESTION # 78
You are troubleshooting a downed BGP session.
Referring to the exhibit, what is the cause of the problem?
- A. The local peer has sent an Update message but not received one from the remote peer.
- B. The TCP session between the peers has not been established.
- C. The UDP session between the peers has not been established.
- D. The local peer has sent an Open message but not received one from the remote peer.
Answer: B
Explanation:
The BGP session in the exhibit shows the state as Connect, which indicates that the TCP session between the BGP peers has not been fully established.
Step-by-Step Breakdown:
BGP State "Connect":
The Connect state is the second stage in the BGP finite state machine (FSM). At this stage, BGP is trying to establish a TCP session with the peer, but the session has not yet been successfully established.
A successful TCP three-way handshake (SYN, SYN-ACK, ACK) is required before BGP can progress to the OpenSent state, where the peers exchange BGP Open messages.
Possible Causes:
A firewall blocking TCP port 179.
Incorrect IP addresses or network connectivity issues between the BGP peers.
Juniper Reference:
BGP Troubleshooting: In Junos, if a BGP session is stuck in the Connect state, the issue is likely due to a failure in establishing the underlying TCP connection.
NEW QUESTION # 79
During a BGP Graceful Restart, what happens to the routes learned from the restarting neighbor?
- A. They are marked as stale but kept in the routing table.
- B. Their metric is increased to prevent their use.
- C. They are immediately removed from the routing table.
- D. They are advertised to other BGP neighbors.
Answer: A
NEW QUESTION # 80
Which two protocols can you use for a data center underlay network? (Choose two)
- A. VXLAN
- B. EBGP
- C. EVPN
- D. OSPF
Answer: B,D
NEW QUESTION # 81
What are two requirements for an IP fabric? (Choose two.)
- A. a Layer 3 routing protocol
- B. a single connection between each spine and leaf
- C. a Layer 2 switching protocol
- D. a single connection between each leaf
Answer: A,B
Explanation:
An IP fabric is a network architecture commonly used in data centers to provide scalable, high-throughput connectivity using a spine-leaf topology.
Step-by-Step Breakdown:
Layer 3 Routing Protocol:
An IP fabric relies on a Layer 3 routing protocol, typically BGP or OSPF, to provide routing between the leaf and spine switches. This ensures efficient traffic forwarding across the network. Single Connection Between Spine and Leaf:
In an IP fabric, each leaf switch connects to every spine switch with a single connection. This ensures that traffic between any two leaf switches can travel through the spine layer in just two hops.
Juniper
Reference: Spine-Leaf Design: Juniper's IP fabric implementations are designed for scalability and low-latency routing, often using protocols like BGP for Layer 3 control.
NEW QUESTION # 82
Which statement is correct about the BGP AS path when advertising routes?
- A. The order of the AS path is only significant in IBGP.
- B. The local AS number is added to the beginning of the AS path.
- C. The local AS number is added to the end of the AS path.
- D. The order of the AS path is not significant.
Answer: B
Explanation:
The BGP AS (Autonomous System) path attribute is crucial in path selection and loop prevention.
Each BGP router appends its local AS number to the beginning of the AS path when it advertises a route to an external BGP (eBGP) peer.
Step-by-Step Breakdown:
AS Path Attribute:
The AS path is a sequence of AS numbers that a route has traversed to reach a destination. Each AS adds its number to the front of the path, allowing BGP to track the route's history.
Why the Local AS is Added at the Beginning:
When advertising a route to an eBGP neighbor, a BGP router adds its own AS number to the beginning of the AS path. This ensures that the AS path reflects the route's journey accurately from the origin to the destination, and prevents loops in BGP. If the route returns to the same AS, the router will detect its AS number in the path and reject the route, preventing routing loops. Order of the AS Path:
The order is significant because BGP uses it to select the best path. A shorter AS path is preferred, as it indicates fewer hops between the source and destination. Juniper Reference: AS Path Attribute: Junos devices append the local AS at the start of the AS path before advertising the route to an external peer.
NEW QUESTION # 83
What is the default Junos behavior of access ports?
- A. Allow a maximum of 80 percent untagged traffic
- B. Allow both tagged and untagged traffic
- C. Allow only untagged traffic
- D. Allow only tagged traffic
Answer: C
NEW QUESTION # 84
What are two reasons why you would deploy an IP fabric instead of a traditional Layer 2 network in a data center? (Choose two.)
- A. Layer 2 networks only support a single broadcast domain.
- B. Layer 3 networks support load balancing.
- C. IP fabrics are better suited to smaller networks where scale is less important.
- D. Layer 2 networks are susceptible to loops.
Answer: B,D
Explanation:
IP fabrics are Layer 3-centric network designs often used in data centers due to their scalability, efficient routing, and loop-free architecture.
Step-by-Step Breakdown:
Layer 3 Load Balancing:
IP fabrics use Equal-Cost Multipath (ECMP) to distribute traffic across multiple paths, providing effective load balancing and improving bandwidth utilization. This capability is absent in traditional Layer 2 networks, which do not support ECMP for routing decisions.
Layer 2 Loops:
Layer 2 networks are prone to loops because of the lack of TTL (Time-to-Live) mechanisms. Spanning Tree Protocol (STP) is required to prevent loops, but it can introduce inefficiencies by blocking links. In contrast, IP fabrics based on Layer 3 protocols are loop-free and do not need STP.
Juniper Reference:
IP Fabric: Juniper's IP fabric solutions offer efficient Layer 3 routing with built-in load balancing and loop prevention, making them ideal for modern data center architectures.
NEW QUESTION # 85
Referring to the exhibit, how many milliseconds will pass before the BGP neighbor is considered dead?
- A. 1000ms
- B. 9000ms
- C. 3000ms
- D. 2000ms
Answer: C
NEW QUESTION # 86
What is a key characteristic of traditional multi-tier data center architectures?
- A. They consist of a modular, scalable design.
- B. They are organized in a hierarchical model with distinct layers.
- C. They exclusively use Layer 3 routing.
- D. They primarily use a flat network design.
Answer: B
NEW QUESTION # 87
Which two prefixes are contributing routes to a 10.20.0.0/18 aggregate route? (Choose two)
- A. 10.20.100.0/24
- B. 10.20.0.0/16
- C. 10.20.0.0/24
- D. 10.20.60.0/23
Answer: C,D
NEW QUESTION # 88
What is the behavior of the default export policy for OSPF?
- A. Forward all routes.
- B. Redistribute all routes.
- C. Reject all routes.
- D. Accept all routes.
Answer: C
Explanation:
In Junos, the default export policy for OSPF is to reject all routes from being exported.
Step-by-Step Breakdown:
Default Export Policy:
By default, OSPF in Junos does not export any routes to other routing protocols or neighbors. This is a safety mechanism to prevent unintended route advertisements.
Custom Export Policies:
If you need to export routes, you must create a custom export policy that explicitly defines which routes to advertise.
Example: You can create an export policy to redistribute static or connected routes into OSPF.
Juniper Reference:
OSPF Export Behavior: In Juniper devices, the default policy for OSPF is to reject route advertisements unless explicitly configured otherwise through custom policies.
NEW QUESTION # 89
Bidirectional Forwarding Detection (BFD) is primarily used for:
- A. Aggregating multiple links
- B. Quick failure detection in forwarding paths
- C. Detecting slow links in the network
- D. Encrypting data packets
Answer: B
NEW QUESTION # 90
What are two device roles in a five-member Virtual Chassis? (Choose two.)
- A. PFE
- B. Routing-engine
- C. Line card
- D. Control-board
Answer: B,C
Explanation:
In a Virtual Chassis (VC) configuration, multiple Juniper switches are interconnected to form a single logical device. Each member switch in the Virtual Chassis plays a specific role.
Step-by-Step Breakdown:
Line Card Role:
Member switches acting as line cards provide additional ports for traffic forwarding but do not perform control or routing functions. These switches depend on the routing engine to handle control-plane tasks.
Routing Engine Role:
A switch in the routing-engine role is responsible for control-plane operations such as routing protocol management and control of the Virtual Chassis.
Virtual Chassis Roles:
Master Routing Engine: Handles control-plane functions and manages the entire Virtual Chassis.
Backup Routing Engine: Takes over if the master fails.
Line Card: Provides additional ports and handles data-plane operations.
Juniper Reference:
Virtual Chassis: In a five-member Virtual Chassis, multiple switches act as line cards, while one or more switches are designated as the routing engines (master and backup).
NEW QUESTION # 91
Which two statements are true about how switches handle Layer 2 traffic? (Choose two.)
- A. The MAC address is learned based on the source MAC address.
- B. Traffic is forwarded based on the destination MAC address.
- C. The MAC address is learned based on the destination MAC address.
- D. Traffic is forwarded based on the source MAC address.
Answer: A,B
Explanation:
In Layer 2 switching, switches learn MAC addresses based on the source MAC address of incoming frames and forward frames based on the destination MAC address.
Step-by-Step Breakdown:
MAC Learning:
When a switch receives a frame, it records the source MAC address and the port on which it arrived.
This allows the switch to know where to send traffic destined for that MAC address.
Forwarding Based on Destination:
The switch then looks at the destination MAC address and forwards the frame out of the port associated with that MAC address. If the MAC is unknown, the switch floods the frame to all ports. Juniper Reference: Layer 2 Switching: Juniper switches use source MAC addresses to build MAC tables and forward traffic based on the destination MAC address.
NEW QUESTION # 92
In the Junos OS, what is the default behavior of a switch when it receives a frame with an unknown destination MAC address?
- A. It discards the frame.
- B. It sends the frame to its default gateway.
- C. It floods the frame out of all ports except the one it was received on.
- D. It buffers the frame until the MAC address can be learned.
Answer: C
NEW QUESTION # 93
In OSPF, what is the function of the Link-State Database (LSDB)?
- A. To keep the topology structure of the network.
- B. To store OSPF routing tables.
- C. To maintain a list of OSPF neighbors.
- D. To log changes in network topology.
Answer: A
NEW QUESTION # 94
Which two statements are correct about rules for EBGP and IBGP? (Choose two.)
- A. EBGP peers have a TTL of 255, while IBGP peers have a TTL of 1.
- B. IBGP routes are more preferred than EBGP routes.
- C. EBGP routes are more preferred than IBGP routes.
- D. EBGP peers have a TTL of 1, while IBGP peers have a TTL of 255.
Answer: C,D
Explanation:
EBGP (External BGP) and IBGP (Internal BGP) operate with different rules due to the nature of their relationships.
Step-by-Step Breakdown:
TTL Differences:
EBGP: By default, EBGP peers have a TTL of 1, meaning they must be directly connected, or the TTL needs to be manually increased for multihop EBGP.
IBGP: IBGP peers within the same AS have a TTL of 255, as they are expected to communicate over multiple hops within the AS.
Preference for EBGP Routes:
Routes learned via EBGP are typically preferred over IBGP routes. This is because EBGP routes are considered more reliable since they originate outside the AS, while IBGP routes are internal. Juniper Reference: BGP Configuration: The different handling of TTL and route preferences between EBGP and IBGP ensures proper route selection and security within Junos-based networks.
NEW QUESTION # 95
Referring to the exhibit, which statement is true?
- A. BFD will bring down the BGP session if no BFD packets are received for 2700 seconds.
- B. BFD only records a syslog message if three BFD packets are missed.
- C. BFD packets are being sent every second.
- D. BFD will bring down the BGP session if no BFD packets are received for 2700 milliseconds.
Answer: D
NEW QUESTION # 96
What happens if a frame with a known destination MAC address enters a switch?
- A. The ingress PFE performs a MAC address lookup and determines the egress PFE and port.
- B. The MAC address is added to the bridge table.
- C. The egress PFE performs a MAC address lookup and determines the ingress PFE and port.
- D. The ingress PFE sends the header information to the RE.
Answer: A
NEW QUESTION # 97
What is the default route preference of a static route in the Junos OS?
- A. 0
- B. 1
- C. 2
- D. 3
Answer: B
Explanation:
In Junos OS, the default route preference for a static route is 5. Route preference values are used to determine which route should be installed in the routing table when multiple routes to the same destination are available.
Step-by-Step Breakdown:
Static Route Preference:
A static route, by default, has a preference of 5, making it a highly preferred route. Lower preference values are more preferred in Junos, meaning static routes take precedence over most dynamic routing protocol routes, such as OSPF (preference 10) or BGP (preference 170).
Route Preference:
Route preference is a key factor in the Junos routing decision process. Routes with lower preference values are preferred and installed in the forwarding table.
Juniper Reference:
Static Routes: In Junos, the default preference for static routes is 5, making them more preferred than most dynamic routes.
NEW QUESTION # 98
What information in the Ethernet header is used to populate the bridging table?
- A. destination address
- B. type
- C. source address
- D. protocol
Answer: C
Explanation:
The source MAC address in the Ethernet header is used to populate the bridging table (also called the MAC address table) on a switch. When a frame arrives at a switch, the switch examines the source MAC address and records it along with the ingress port in its MAC address table.
Step-by-Step Breakdown:
Learning Process:
When an Ethernet frame arrives on a switch port, the switch looks at the source MAC address and adds this MAC address to the MAC table along with the port it was received on. This process is called MAC learning.
Purpose:
The switch uses this information to determine the correct port to send frames destined for that MAC address in future transmissions, thus ensuring efficient Layer 2 forwarding.
Juniper Reference:
Ethernet Switching: Juniper switches use source MAC addresses to build and maintain the MAC address table, which is essential for Layer 2 switching.
NEW QUESTION # 99
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