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CCENT Quick Reference Sheets by Jim Doherty, Eric Rivard

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Section 5. Operating Cisco IOS

Cisco IOS enables network services in switches and routers. It provides the following features:

  • Carries network protocols and functions
  • Connectivity
  • Security
  • Scalability
  • Reliability

The Cisco IOS command-line interface (CLI) can be accessed through a console connection, modem connection, or Telnet/SSH sessions. These connections are called EXEC sessions.

Cisco Device Startup

When a Cisco device starts up, it goes through the following steps:

Step 1. Completes power-on self test (POST)

Step 2. Finds and loads Cisco IOS Software image

Step 3. Finds and applies device configuration

External Configuration Sources

An IOS device can be configured from any of the following external sources:

  • Console terminal
  • Remote terminal ...

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