S1 / 02 MODULE 2 / CISCO IOS FUNDAMENTALS
Learn the IOS command hierarchy, configure a switch or router safely, save changes, and verify management connectivity.
Cisco IOS separates command-line access into modes. User EXEC mode is the limited starting mode, shown by the > prompt. Privileged EXEC mode is shown by # and provides access to monitoring and administrative commands. Use enable to enter privileged EXEC mode. Use configure terminal to enter global configuration mode, where device-wide settings are changed.
IMG-0103The prompt identifies the current mode. Global configuration mode uses (config)#. Interface configuration uses (config-if)#, and line configuration uses (config-line)#. A command consists of a command name plus any required keywords and arguments. Context-sensitive help uses ? to show available commands, keywords, and arguments for the current mode. For example, enter interface ? at Switch(config)# to list valid interface types in that context. Tab completes a command prefix only when it uniquely identifies the command; if the prefix is ambiguous, use ? to inspect the available choices. When output pauses at --More--, Space advances a page and Enter advances a line.
IMG-0109A basic switch or router setup commonly includes a meaningful hostname, a protected privileged EXEC password using enable secret, console and remote-line settings, and a login banner. Configure console access under line console 0. Configure remote terminal access under line vty. The login command requires a line password; login local uses the local username database. service password-encryption obscures supported plaintext line passwords in the configuration, but it is not a replacement for strong secrets or secure management protocols.
IMG-0117The running-config is the active configuration held in RAM. Changes affect the device immediately but can be lost after a restart if they are not saved. The startup-config is stored in NVRAM and is loaded during boot. Save the active configuration with copy running-config startup-config. Verify saved and active settings with show startup-config and show running-config.
IMG-0136An IPv4 address is represented in dotted-decimal notation as four decimal octets, each from 0 through 255. A 32-bit subnet mask identifies the network and host portions of the address. A default gateway is the router address a host uses to reach destinations outside its local subnet. A Layer 2 switch can be assigned a management IP address on an SVI such as interface vlan 1, with no shutdown, and an ip default-gateway for remote management.
IMG-0116Use show ip interface brief to inspect interface names, assigned IP addresses, administrative/operational status, and line protocol state. Use ping to test reachability and traceroute (tracert on Windows) to examine the path toward a destination. A successful interface configuration does not by itself prove end-to-end connectivity; check addressing, masks, gateway settings, link state, and the remote path.
IMG-0120COMMAND QUICK REFERENCE
enableEnter privileged EXEC mode.configure terminalEnter global configuration mode.interface ?Show valid interface types in the current configuration context.TabComplete a command prefix when it uniquely identifies a command.show running-configDisplay the active configuration.copy running-config startup-configSave active settings to startup configuration.show ip interface briefSummarize interface addresses and status.service password-encryptionObscure supported plaintext passwords in configuration output.CHECK YOUR UNDERSTANDING
Practice questions target IOS modes, configuration persistence, addressing, and verification.