In Junos OS, as with many network operating systems, the control plane is responsible for processes that determine how to route traffic. This includes maintaining routing tables, which store information about network paths and protocols. Therefore, routing tables are indeed stored in the control plane.
Exception traffic refers to packets that cannot be processed by the normal fast-path processing of the Packet Forwarding Engine (PFE) in the forwarding plane, and thus are sent to the control plane for further processing. This might include packets destined for the router itself, packets that need to be fragmented, or packets that match certain firewall filter criteria, among other reasons.
Routing tables are not stored in the forwarding plane. However, the forwarding plane contains the forwarding table (sometimes referred to as the forwarding information base or FIB), which is a distilled version of the routing table optimized for fast packet forwarding. The forwarding plane uses this information to perform the actual transfer of packets across the network device interfaces.
Questions 5
You have configured some interfaces on a Junos device; however, you have not yet committed the configuration.
What happens if you issue the rollback 0 command in this scenario?
Issuing the rollback 0 command in Junos OS will discard any uncommitted changes and revert to the last committed configuration. This command effectively cancels any configuration changes that have been made but not yet committed, ensuring that the device returns to its previous stable state.
References:
"rollback 0 ...................................(rolls back the changes just made )" from Useful Juniper Commands.txt.
Juniper official documentation: Rolling Back a Configuration.
Questions 6
Which two statements are correct about MAC addresses? (Choose two.)
Options:
A.
Switches use the Address Resolution Protocol table to assign MAC addresses to network interface cards in the forwarding frame.
B.
The source and destination MAC addresses always remains static to the final destination.
C.
The MAC address identifies the physical hardware.
D.
Switches use the destination MAC address to identify the next-hop destination and to change the destination MAC address in the frame.
MAC (Media Access Control) addresses are unique identifiers assigned to network interfaces for communications at the data link layer of a network segment. MAC addresses are used to identify the physical hardware on a network. In the context of Ethernet switches, the destination MAC address in incoming frames is used to determine the appropriate output port for forwarding the frame towards its final destination. The switch does not change the destination MAC address; it uses the MAC address to make forwarding decisions within the local network segment.
Questions 7
Which protocol is responsible for learning an IPv4 neighbor's MAC address?
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.
