Before moving towards the commands that every network admin should acknowledge, let us delve into the CISO internetwork operating system. It is a collection of network operating systems used on several Cisco Systems routers and new Cisco network switches. IOS is a package of functions combining routing, switching, internetworking and telecommunications into a multitasking operating system. While a cooperative multitasking kernel is included in the IOS code base, most IOS features have been ported to other kernels, such as QNX and Linux, for use in Cisco products. Connect with our experts to learn more about our IT certifications.
Becoming an expert with IOS means learning some prerequisite commands. Although, it is challenging to configure thousands of commands that CISO anticipates. But the five most important commands are described in this article. Even if you are new to CISO administration, these commands are helpful.
5 Cisco IOS Commands for Network Admin
IOS: Command # 1 (show running-config)
Show running-config is perhaps the most useful of all the commands from Cisco. You get to see the router's entire active configuration with this instruction. Any command that you type is shown. Each default command has been applied. With a single IOS button, all this great information is open. It's so easy. IP addresses, interfaces, passwords (in plain text), routing protocols and other settings can be accessed. This command can only be used in Privileged EXEC mode.
This command displays the current configuration of the router, switch or firewall. Running-configuration is the configuration that is in the memory of the router. When you make adjustments to the router, you alter this configuration. Bear in mind that the configuration is not saved until you copy the start-up configuration-start-configuration configuration.
You may abbreviate this order as sh run or wr t.
IOS: Command # 2 (show IP interface brief)
Show interface commands provide you a lot of information about all the interfaces of your router. To answer the questions, you often want clear, detailed information: Is the interface up to date? What are the IP addresses that the interfaces are allocated to? The Display IP interface brief command provides you with answers to these questions and is the best description of your interfaces' status, protocol and IP addresses. You may use this command both in the User EXEC and the Privileged EXEC mode.
The Display IP interface command offers lots of useful information on all interfaces about the configuration and status of the IP protocol and its services. The display IP interface brief command provides a short status, including its IP address, Layer 2 status, and Layer 3 status, for the interfaces on the router. Show IP interface brief is more popular than show interface and show IP interface.
Sh ip int brie can be abbreviated with this instruction.
IOS: Command # 3 (show IP route)
Routers learn about networks, either statically or dynamically, and store in their routing table the best route to those networks. Once you know that your interfaces are up and your configuration is saved, you want to check that your router has convergence, which means that your router has correct network accessibility information. The view IP route command shows the method used to learn about these networks, the next-hop IP address and the local interface used to get to all known connected and destination networks. You may use this command in both the User-EXEC and Privileged EXEC modes.
The show IP route command is used to view the router's routing table. This is the list of all networks that can be accessed by the router, their metric (the choice of the router for them) and how to get there. This command can be abbreviated to shipro, and like shiproospff for all OSPF routers, it can have parameters after it. You clear the IP route * to clear the routing table of all paths. To clear it from only one path, clear the IP route 1.1.1.1 to clear the specific network.
You can abbreviate this order as sh ip ro.
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IOS: Command # 4 (copy running-config startup-config)
It’s important to remember the changes that you made to your router’s configuration. This command copies the active RAM running configuration you have changed to the flash memory startup configuration. By copying the configuration to a flash, when the router is turned off and restarted, it will be saved. This command can be used only in Privileged EXEC mode.
This command saves the configuration that is currently being changed (in RAM) to nonvolatile RAM, also known as the running configuration (NVRAM). The NVRAM will maintain this configuration if the power is lost. In other words, if you modify the configuration of the router, do not use this command and reboot the router, as you will lose those changes. You may abbreviate this command to Copy Start Run. In case anything happens to the router, the copy command may also be used to copy the running or startup configuration from the router to a TFTP server.
The shortcut to this command is wr, wr (which is short for write memory).
IOS: Command # 5 (show interface)
The display interface command shows the status of the interfaces of a router. This performance, amongst other items, provides the following:
- State of the interface (up/down)
- State of the protocol on an interface
- Utilization
- Mistakes
- The MTU
This command is critical for troubleshooting a router or switch. It can also be used to define a certain GUI, such as fa0/0.0 shint.
It is worth knowing what kind of interfaces are on your router, important statistics on those interfaces, and whether they are up or down. The Display Interfaces command is a very verbose command with a lot of performance. You can select the output to find what you are looking for, and the output of this command shows just about everything relevant to interfaces, such as interface form, speed, IP address and interface errors. You may use this command both in the User EXEC and the Privileged EXEC mode.
It's possible to abbreviate this command as sh int.
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