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That `>` is your entry point. You're at the user EXEC prompt — the lowest privilege level, useful for a handful of `show` commands and not much else. To go anywhere meaningful, you enter privileged mode with `enable`.
IOS is a monolithic operating system. The kernel, device drivers, and process scheduler are bundled with the routing and switching software into a single image file (`.bin`) that lives in flash. There's no package manager, no container — one image, one revision, reboot to change it.
Configuration is stored separately in two places: `running-config` in RAM (the live config) and `startup-config` in NVRAM (the saved config loaded at boot). Changes you make are live in running-config immediately; they're only persistent after a `write memory` or `copy running-config startup-config`.
| Prompt | Mode | Purpose | Entry command |
|---|---|---|---|
| Router> | User EXEC | Limited show, ping, traceroute | Initial login |
| Router# | Privileged EXEC | All show, debug, copy, reload | `enable` |
| Router(config)# | Global config | Device-wide settings | `configure terminal` |
| Router(config-if)# | Interface config | Per-interface settings | `interface <name>` |
| Router(config-router)# | Router config | Routing protocol settings | `router ospf 1` |
| Router(config-line)# | Line config | Console, VTY, AUX | `line console 0` |
| Router(config-vlan)# | VLAN config | VLAN database | `vlan 10` |
Note that config mode is modal — you have to be in the right submode to run the right commands. If IOS rejects a command with `% Invalid input detected`, you're almost always in the wrong submode. Type `exit` until you see the prompt you need.
`?` shows every valid completion at the current context. If it returns nothing, you're in the wrong mode or the command doesn't exist in this IOS version. This is the fastest way to discover commands you half-remember.
Learn the escape sequences early: `Ctrl+A` jumps to start of line, `Ctrl+E` to end, `Ctrl+Z` exits to privileged EXEC from anywhere, `Ctrl+C` cancels current command, `Tab` completes. These save hours over a career.
Next lesson goes deeper into the three privilege levels and what each can do.
Finish the lesson once you have worked through the material. This awards ★ 30 XP.