JN0-105 Practice Questions

In Junos OS, to navigate from operational mode to configuration mode, you can use either the edit or

configure command. Both commands move the CLI from operational mode, where you can view the

state of the device, to configuration mode, where you can make changes to the device's

configuration.

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.

In the exhibit shown, the highlighted number next to the route type (Static) within the square

brackets indicates the route preference, also known as the administrative distance. In Junos, the

route preference is a value that determines the priority of the route source. Lower numbers indicate

a higher priority when the routing table is being calculated. The route preference is used to select the

best route when multiple paths to the same destination exist from different routing sources. The

number 5 is unusually low for a static route by default, suggesting it has been manually configured to

override other route types.

The Network Time Protocol (NTP) is designed to synchronize the clocks of computers over a network.

Configuring NTP on a Junos device ensures that its clock is set accurately, which is crucial for logging,

troubleshooting, and maintaining the integrity of time-sensitive operations and security protocols.

NTP allows devices to use a hierarchy of time sources, from primary servers synchronized to a

reference clock (such as an atomic clock or GPS time) to secondary servers that distribute the time to

other devices on the network.

In the Junos OS command-line interface (CLI), the keyboard shortcut Ctrl+a is used to move the

cursor to the start of the line. This is a common convention in many command-line environments and

text editors, providing a quick way to navigate to the beginning of the current command or line of

text without having to use the arrow keys. This can be particularly useful for making quick edits to

commands or for navigating long lines of text more efficiently.

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.

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.

In Junos OS, route preference (also known as administrative distance) is used to determine the

preferred route among multiple routes to the same destination learned via different routing

protocols. Direct and local routes, which represent directly connected networks and interfaces,

typically share the same low preference value, indicating high trustworthiness because they are

directly connected to the router. OSPF internal routes (routes within the same OSPF area) and OSPF

AS external routes (routes that are external to the OSPF autonomous system but redistributed into

OSPF) also share the same preference value, although this value is higher (indicating less trust) than

for direct and local routes. This distinction helps the routing engine decide which routes to use when

multiple paths are available.

When configuring the system-related settings for the current date and time on a Junos device,

especially for a specific time zone like America/Los_Angeles, and the time does not automatically

adjust, two effective actions can be taken. Firstly, setting the date and time manually allows for

immediate correction of the system clock. This can be done via the CLI with the appropriate set date

and time command. Secondly, configuring the device to use an NTP server can provide ongoing

synchronization with an accurate time source, ensuring that the device maintains the correct time

and date automatically in the future, even in the case of restarts or minor drifts in the internal clock.

An Ethernet frame header includes the source MAC address (B) and the destination MAC address (D).

These addresses are used to deliver the frame from one Ethernet device to another directly

connected Ethernet device on the same network segment. Ethernet frames do not include IP

addresses, as those are part of the IP packet encapsulated within the Ethernet frame.