Question 1

Which two functions are performed by the PFE? (Choose two.)

Accepted Answer

The Packet Forwarding Engine (PFE) in Junos OS performs several key functions, including implementing firewall filters (A) and forwarding transit traffic (C). The
PFE applies firewall filter rules to incoming and outgoing traffic and is responsible for the high-speed forwarding of packets based on the information in the
forwarding table.

Question 2

Which statement is correct when multiple users are configuring a Junos device using the configure private command?

Accepted Answer

When multiple users are configuring a Junos device using the "configure private" command, each user gets their own candidate configuration (C). This allows for
isolated configuration sessions, where changes made by one user do not impact or interfere with the changes made by another user in their private session.

Question 3

Which two statements are correct regarding Layer 2 network switches? (Choose two.)

Accepted Answer

Layer 2 network switches are crucial components in local area networks (LANs), providing multiple functions for data packet forwarding and network
segmentation. One inherent characteristic of switches is their susceptibility to traffic loops, especially in networks with redundant paths. Without proper loop
prevention protocols like Spanning Tree Protocol (STP), loops can cause broadcast storms and network instability. Additionally, switches inherently flood
broadcast traffic to all ports within the broadcast
domain, except the port on which the broadcast was received. This is because broadcast frames are meant to be delivered to all devices within the VLAN, and the
switch ensures this by flooding these frames to all ports in the VLAN, except the source port.

Question 4

What information does the forwarding table require so that the device forwards traffic? (Choose three.)

Accepted Answer

The forwarding table in a network device requires specific information to efficiently forward traffic toward its destination. This includes the next hop IP address,
which indicates the next router or device in the path to the destination. The outgoing interface name identifies the physical or logical interface through which the
packet should be sent to reach the next hop. Lastly, the next hop MAC address is crucial for Layer 2 forwarding decisions, allowing the device to encapsulate the
IP packet in a frame that can be understood by Ethernet or other Layer 2 protocols. OSPF metric values and BGP local
preference values are used in the routing decision process to select the best path and populate the forwarding table but are not directly used by the forwarding
table to forward traffic.

Question 5

When considering routing policies, which two statements are correct? (Choose two.)

Accepted Answer

Routing policies in Junos OS are crucial for controlling route advertisements and path selection. The correct answers are B and C. An import routing policy for
BGP determines which received prefix advertisements are placed in the routing information base (RIB), and policy terms are evaluated from top to bottom, with
action taken on the first match found. This sequential evaluation allows for precise control over routing decisions.

Question 6

What are two attributes of the UDP protocol? (Choose two.)

Accepted Answer

UDP (User Datagram Protocol) is known for being connectionless (D) and providing best-effort delivery without the reliability mechanisms present in TCP (C). This
means that UDP does not establish a connection before sending data and does not guarantee delivery, order, or error checking, making it faster but less reliable
than TCP.

Question 7

Which prompt indicates that you are using configuration mode?

Accepted Answer

In Junos OS, the # prompt indicates that you are in configuration mode. This mode is used for making changes to the configuration of the device.
Reference: Juniper Networks CLI Modes
"The # prompt indicates that you are in configuration mode."

Question 8

Which protocol is responsible for learning an IPv4 neighbor's MAC address?

Accepted Answer

The Address Resolution Protocol (ARP) is responsible for mapping an IPv4 address to a machine's MAC address. ARP operates at Layer 2 of the OSI model and
is used to find the MAC address of a host given its IPv4 address. When a device wants to communicate with another device on the same local network, it uses
ARP to discover the recipient's MAC address.
References:
? Juniper official documentation: ARP.
? Networking standards: RFC 826.

Question 9

Which statement is correct concerning exception traffic processing?

Accepted Answer

Exception traffic refers to packets that the Packet Forwarding Engine (PFE) cannot process normally and must be forwarded to the Routing Engine (RE) for further
processing. This includes packets destined for the router itself or packets needing special handling that the PFE cannot provide. To protect the RE from being
overwhelmed by such traffic, which could potentially impact the router's control plane functions, exception traffic is rate-limited. This means that there's a threshold
to how much exception traffic can be sent to the RE, ensuring that the router's critical management and control functions remain stable and responsive even during
high traffic volumes or attacks.

Question 10

Which Junos feature limits the amount of exception traffic that is sent from the PFE to the RE?

Accepted Answer

In Junos OS, a policer is a feature used to limit the rate of traffic flow in the network, including exception traffic sent from the Packet Forwarding Engine (PFE) to
the Routing Engine (RE). Exception traffic consists of packets that cannot be processed by the PFE alone and require intervention by the RE, such as control
packets or packets destined for the device itself. A policer can be configured to enforce bandwidth limits and drop or mark packets that exceed specified rate limits,
thus protecting the RE from being overwhelmed by excessive exception traffic.