2.1 Junos OS Fundamentals: Architecture & Core Daemons Flashcards
(21 cards)
What kernel is the Junos OS based on?
FreeBSD — a Unix-based operating system.
Why is Junos OS considered stable?
It separates system functions into isolated processes (daemons), so a crash in one doesn’t affect others.
What benefit comes from Junos OS running on all Juniper devices?
It provides a consistent CLI and behavior across platforms, simplifying management and configuration.
How does Junos OS differ from Cisco in terms of OS across platforms?
Junos uses one OS for all devices; Cisco uses different OS versions for Nexus and Catalyst switches.
What is a daemon in Junos OS?
A background software process responsible for specific functions (e.g., routing, management).
What does the RPD daemon do?
Routing Protocol Daemon — manages routing protocols, updates routing tables, and applies routing policies.
Where does the RPD run in the architecture?
In the Routing Engine (RE) of the device.
What is the purpose of the MGD daemon?
Management Daemon — handles user access via CLI/SSH/API and brokers communication between users and internal processes.
How does the MGD daemon serve external users?
It collects data for show commands and applies changes in configuration mode.
What does the DCD (Device Control Daemon) do?
It manages physical interfaces and hardware detection/configuration based on system configuration.
Can you configure hardware that isn’t present yet on a Juniper device?
Yes — Junos allows configuration of non-present hardware, which the DCD applies once hardware is inserted.
What is dynamic routing in Junos OS?
Routing protocols automatically share route information between routers so manual configuration of routes isn’t needed.
Why is daemon isolation important in Junos OS?
A failure in one daemon (e.g., SNMP) won’t affect others (e.g., RPD), maintaining system stability.
What is the name of the SNMP daemon in Junos?
snmpd — the background process handling SNMP polling and traps.
What role does the console port play in Junos management?
It allows direct, local access to the CLI, managed by the MGD daemon.
What is the difference between operational mode and configuration mode in Junos?
Operational mode is for monitoring (show commands), configuration mode is for changing system settings.
Which daemon is responsible for CLI command processing?
MGD — it interprets CLI input and routes it to the correct process or daemon.
How does Junos handle daemon crashes?
Each daemon is isolated, so a crash in one doesn’t crash the whole system. It can often restart without rebooting the device.
What is the advantage of running the same OS on Juniper switches, routers, and firewalls?
It allows administrators to apply the same commands and workflows across all platforms.
What does the Device Control Daemon configure?
Interfaces and physical hardware based on the active configuration and installed components.
Which daemon handles route advertisements and updates?
RPD — the Routing Protocol Daemon.
