In Juniper Networks devices, when the factory default configuration is loaded, the first step before

committing any configuration is to set up root authentication. This is crucial because it secures the

device by ensuring that only authorized users have administrative access. Without setting up a root

password, the device will not allow any commit operations, which is a safety measure to prevent

unauthorized access. This requirement emphasizes the importance Juniper places on security right

from the initial setup of the device.

One of the key advantages of Junos OS is its ability to roll back to previous configurations. This

feature allows administrators to revert to an earlier configuration state, which is invaluable for

quickly recovering from configuration errors or undesired changes. Junos OS maintains an archive of

previous configurations, enabling easy rollback to any saved state. Another significant advantage of

Junos OS is its modular design. The operating system is structured so that different processes and

services run in separate protected memory spaces, enhancing the stability and reliability of the

system. If one process fails, it does not affect the others, thereby minimizing the risk of system-wide

failures.

https://www.juniper.net/documentation/us/en/software/junos/user-access-evo/user-

access/topics/topic-map/junos-os-login-

class.html#:~:text=You%20can%20define%20any%20number,to%20an%20individual%20user%20acc

ount.

In Junos OS, each user account can be assigned only one login class. Login classes in Junos OS define

the permissions for users, controlling what they can access and modify within the system. This setup

helps in maintaining a clear and secure access control mechanism.

Reference:

Junos OS Documentation on User Accounts and Login Classes.

In Juniper firewall filter configurations, "discard" and "accept" are two valid terminating actions for a

term within a filter. The "discard" action drops the packet, preventing it from reaching its intended

destination, while the "accept" action allows the packet to pass through the filter, proceeding to its

next hop or destination. "Count" is a non-terminating action that increments a counter every time a

packet matches the term but does not inherently determine the packet's fate. "Next term" directs

the evaluation to proceed to the next term in the filter for further processing, also a non-terminating

action.

In Junos OS, when creating a new user account, the minimum required fields are the username and

the login class. The username is the identifier for the account, while the login class specifies the level

of access or permissions the user has on the device. Login classes allow for the differentiation

between various roles, such as read-only access or full administrative rights. Other information, such

as full name or user ID, is optional and not strictly necessary for the creation of a functional user

account.

When you enter ? at the command-line prompt in Junos OS, the system provides assistance in two

significant ways. Firstly, it lists the available commands and options that can be used at the current

point in the command hierarchy, aiding users in understanding what commands they can execute

next. Secondly, it displays summary information about those commands and options, providing brief

descriptions or additional context that can help users understand the function of each command or

option. This feature is particularly useful for learning the command structure or for quick reference

when specific command syntax is forgotten.

Referring to the firewall filter configuration in the exhibit, when a packet matches the specified term

limit-icmp, two actions are defined in the then statement: count count-icmp and discard. The count

count-icmp action means that each time a packet matches this term, a counter named count-icmp

will be incremented, providing a tally of how many packets have matched the term. The discard

action means that the packet will be dropped and not forwarded through the device. This effectively

prevents the packet from reaching its intended destination. There is no action specified that would

cause an ICMP destination unreachable message to be returned, nor is there any action that would

allow the packet to be forwarded.

To view real-time usage statistics for the busiest interfaces on a device running Junos OS, the correct

command is B, "monitor interface traffic." This command provides a dynamic, real-time view of the

traffic flowing through the interfaces, allowing administrators to quickly identify and monitor the

busiest interfaces on the device.

After increasing the MTU size of an interface and committing the configuration, the command to

verify the applied MTU change is D, "show interfaces ge-0/0/0." This command displays detailed

information about the interface, including the current MTU size, making it the best choice for

verifying the applied changes.

When an interface on a router is configured with an IPv4 address and is in an up state, two types of

routes are automatically created in the routing table: a local route and a direct route, making B and D

the correct answers. The local route represents the interface's IP address itself, indicating that the

router can directly receive packets addressed to this IP. The direct route represents the subnet or

network segment to which the interface is connected, indicating that the router can directly forward

packets to destinations within this subnet.