One of your company’s headquarters routers is not forwarding packets to a branch location. The router is housed in a locked room onsite. A junior administrator has remotely connected to the router to troubleshoot the problem. You have been asked for assistance in interpreting some of the configuration output.
Which of the following methods are you least likely to use to connect to the router? (Select the best answer.)
- a console port
- a serial port
- an auxiliary port
Of the available choices, you are least likely to use a serial port to connect to the router. Serial ports and Ethernet ports are used to directly connect Cisco routers to other network devices. For example, you might use a serial port to directly connect a Cisco router to other data terminal equipment (DTE) or data communications equipment (DCE) devices. You would also use a serial port to connect a router to a Channel Service Unit/Data Service Unit (CSU/DSU).
You are likely to use inband tools, such as Telnet or Secure Shell (SSH), to connect to the router in this scenario because the router is remotely accessible from your company’s network. Management applications and administrators who want to manage a Cisco device when it is operating in its normal state could connect to the device by using virtual terminal (VTY) application protocols such as Telnet or SSH. The use of VTY lines typically allows multiple administrators or management applications to concurrently access a device from more than one location.
You might use a console port or an auxiliary (AUX) port to connect to the router in this scenario, although doing so is not necessary because the router is remotely accessible. In addition, connecting by either of these methods requires you to be in the same room as the device. You are most likely to use either an AUX port or a console port to manage a Cisco router outofband, such as when the router is in readonly memory (ROM) monitor (ROMmon) mode. The AUX port on a Cisco router is typically capable of supporting most of the features available on a console port. Cisco switches either do not have AUX ports or do not support certain features, such as system recovery, on their AUX ports if they have them.
ROMmon is a management mode that Cisco routers and switches revert to when the system cannot find a software image, the software image is corrupted, or the configuration register has been set to manually enter ROMmon mode. Because ROMmon is an outofband management method, it can be used to recover system software images, passwords, or other configuration data even when the router or switch is in a state where it can no longer forward packets.