Juniper JunOS
The command-line world network engineers live in when configuring Juniper routers and switches.
What it is
About Juniper JunOS
JunOS is Juniper Networks' FreeBSD-based operating system for its routers, switches and security appliances, known for its consistent, hierarchical CLI and a unique commit model that lets engineers stage and validate configuration changes before applying them. It's a major alternative to Cisco IOS in service-provider and large enterprise networks, and heavily tested in networking certifications (JNCIA, JNCIS and JNCIE). Engineers use it to configure routing protocols (BGP, OSPF), VLANs, firewall policies and MPLS.
What you can do with it
Capabilities
Configure and troubleshoot routing protocols (BGP, OSPF, IS-IS) on Juniper devices
Set up VLANs, firewall filters and security zones
Use the commit and rollback model to stage and safely test configuration changes
Automate configuration with JunOS's native scripting (SLAX and Python) and NETCONF and REST APIs
Monitor and troubleshoot network performance and traffic flows
How to learn it
Learning Resources
Juniper's own JNCIA-Junos free certification training and exam
Juniper vLabs (free virtual lab environment)
Official Juniper Networks documentation and Day One books (free PDFs)
Practise labs using GNS3 and EVE-NG with vMX and vJunos virtual images
Pro Tip
Get comfortable with 'commit confirmed' early — it auto-rolls back a change if you don't confirm within a set time, which has saved countless engineers from locking themselves out of a remote device.
Skills that use this tool
Roles that use this tool