Course Content
Networking Today
0/7
Network Components
Network Representations and Topologies
Common Types of Networks
Internet Connections
Reliable Networks
Network Security Basic
Network Trends
Basic Switch and End Device Configuration
0/7
Cisco IOS Access
Cisco IOS Navigation
Cisco IOS Command Structure
Basic Cisco Device Configuration
Save Cisco IOS Configurations
Ports and Addresses
Configure IP Addressing
Protocols and Models
0/7
The Rules in Network Communications
Protocols
Protocol Suites
Standards Organizations
Reference Models
Data Encapsulation
Data Access
Physical Layer
0/6
Purpose of the Physical Layer
Physical Layer Characteristics
Copper Cabling
UTP Cabling
Fiber-Optic Cabling
Wireless Media
Data Link Layer
0/3
Purpose of the Data Link Layer
WAN and LAN topologies
Data Link Frame
Ethernet Switching
0/4
Ethernet Frames
Ethernet MAC Address
The MAC Address Table
Switch Speeds and Forwarding Methods
Network Layer
0/5
Network Layer Characteristics
IPv4 Packet
IPv6 Packet
How a Host Routes
Router Routing Tables
Number Systems
0/2
Binary Number System
Hexadecimal Number System
Address Resolution
Explain how ARP and ND enable communication on a network
0/3
MAC and IP
ARP
Neighbor Discovery
Basic Router Configuration
0/3
Configure Initial Router Settings
Configure Interfaces
Configure the Default Gateway
IPv4 Addressing
0/7
IPv4 Address Structure
IPv4 Unicast, Broadcast, and Multicast
Types of IPv4 Addresses
Network Segmentation
Subnet an IPv4 Network
VLSM
Structured Design
IPv6 Addressing
0/8
IPv4 Issues
IPv6 Address Representation
IPv6 Address Types
GUA and LLA Static Configuration
Dynamic Addressing for IPv6 GUAs
Dynamic Addressing for IPv6 LLAs
IPv6 Multicast Addresses
Subnet an IPv6 Network
ICMP
0/2
ICMP Messages
Ping and Traceroute Testing
Transport Layer
0/7
Transportation of Data
TCP Overview
UDP Overview
Port Numbers
TCP Communication Process
Reliability and Flow Control
UDP Communication
Application Layer
0/7
Application, Presentation, and Session
Peer-to-Peer
Web Protocols
Email Protocols
Dynamic Host Configuration Protocol (DHCP)
Domain Name Service
File Sharing Services
Network Security Fundamentals
0/4
Security Threats and Vulnerabilities
Network Attacks
Network Attack Mitigation
Device Security
Build a Small Network
0/7
Devices in a Small Network
Small Network Applications and Protocols
Scale to Larger Networks
Verify Connectivity
Host and IOS Commands
Troubleshooting Methodologies
Troubleshooting Scenarios
Basic Device Configuration
0/5
Configure a Switch with Initial Settings
Configure Switch Ports
Secure Remote Access
Basic Router Configuration
Verify Directly Connected Networks
CCNA: Switching, Routing, and Wireless Essentials
The second course in the CCNA curriculum focuses on switching technologies and router operations that support small-to-medium business networks and includes wireless local area networks (WLAN) and security concepts.
0/15
Switching Concepts
VLANs
Inter-VLAN Routing
STP
Etherchannel
DHCPv4
SLAAC and DHCPv6 Concepts
FHRP Concepts
LAN Security Concepts
Switch Security Configuration
WLAN Concepts
WLAN Configuration
Routing Concepts
IP Static Routing
Troubleshoot Static and Default Routes
CCNA: Enterprise Networking, Security, and Automation
The third CCNA course describes the architectures and considerations related to designing, securing, operating, and troubleshooting enterprise networks – including wide area network (WAN) technologies & quality of service (QoS) mechanisms for secure remote access, along with software-defined networking, virtualization, & automation concepts supporting network digitization.
0/14
Single-Area OSPFv2 Concepts
Single-Area OSPFv2 Configuration
Network Security Concepts
ACLs Concepts
ACLS for IPv4 Configuration
NAT for IPv4
WAN Concepts
VPN and IPsec Concepts
QoS Concepts
Network Management
Network Design
Network Troubleshooting
Network Virtualization
Network Automation
CCNA Course
About Lesson

Cisco IOS Command Structure

Describe the command structure of Cisco IOS software.

Basic IOS Command Structure

  • Keyword – This is a specific parameter defined in the operating system (in the figure, ip protocols).
  • Argument – This is not predefined; it is a value or variable defined by the user (in the figure, 192.168.10.5).

IOS Command Syntax Check

A command might require one or more arguments. To determine the keywords and arguments required for a command, refer to the command syntax.

  • Boldface text indicates commands and keywords that are entered as shown.
  • Italic text indicates an argument for which the user provides the value.
Convention Description
boldface Boldface text indicates commands and keywords that you enter literally as shown.
italics Italic text indicates arguments for which you supply values.
[x] Square brackets indicate an optional element (keyword or argument).
{x} Braces indicate a required element (keyword or argument).
[x {y | z}] Braces and vertical lines within square brackets indicate a required choice within an optional element. Spaces are used to clearly delineate parts of the command.
  • The command syntax provides the pattern, or format, that must be used when entering a command. The command is ping and the user-defined argument is the ip-address of the destination device. For example, ping 10.10.10.5.

  • The command is traceroute and the user-defined argument is the ip-address of the destination device. For example, traceroute 192.168.254.254.

  • If a command is complex with multiple arguments, you may see it represented like this:

IOS Help Features

The IOS has two forms of help available: context-sensitive help and command syntax check. Context-sensitive help enables you to quickly find answers to these questions:

  • Which commands are available in each command mode?
  • Which commands start with specific characters or group of characters?
  • Which arguments and keywords are available to particular commands?

 

  • Command syntax check verifies that a valid command was entered by the user. If the interpreter cannot understand the command being entered, it will provide feedback describing what is wrong with the command.

Hot Keys and Shortcuts

  • The IOS CLI provides hot keys and shortcuts that make configuring, monitoring, and troubleshooting easier.
  • Commands and keywords can be shortened to the minimum number of characters that identify a unique selection. For example, the configure command can be shortened to conf because configure is the only command that begins with conf.

  • The table below is a brief list of keystrokes to enhance command line editing.
Keystroke Description
Tab Completes a partial command name entry.
Backspace Erases the character to the left of the cursor.
Left Arrow or Ctrl+B Moves the cursor one character to the left.
Right Arrow or Ctrl+F Moves the cursor one character to the right.
Up Arrow or Ctrl+P Recalls the commands in the history buffer, beginning with the most recent commands.
  • When a command output produces more text than can be displayed in a terminal window, the IOS will display a “–More–” prompt. The table below describes the keystrokes that can be used when this prompt is displayed
Keystroke Description
Enter Key Displays the next line.
Space Bar Displays the next screen.
Any other key Ends the display string, returning to privileged EXEC mode.
  • The table below lists commands that can be used to exit out of an operation.
Keystroke Description
Ctrl-C When in any configuration mode, ends the configuration mode and returns to privileged EXEC mode.
Ctrl-Z When in any configuration mode, ends the configuration mode and returns to privileged EXEC mode.
Ctrl-Shift-6 All-purpose break sequence used to abort DNS lookups, traceroutes, pings, etc.

 

Other related topics

 

Topic Title Topic Objective
Cisco IOS Access Explain how to access a Cisco IOS device for configuration purposes.
Cisco IOS Navigation Explain how to navigate Cisco IOS to configure network devices.
Cisco IOS Command Structure Describe the command structure of Cisco IOS software.
Basic Cisco Device Configuration Configure a Cisco IOS device using CLI.
Save Cisco IOS Configurations Use IOS commands to save the running configuration.
Ports and Addresses Explain how devices communicate across network media.
Configure IP Addressing Configure a host device with an IP address.

Other useful information

 

Join the conversation
Previous
Next