Router Components & Boot Sequence

Question 1

What places and in what order will a router look for an ios image when you start it up?

Answer 1

Flash, a designated tftp server, ROM

Question 2

What does RAM stand for, and what things are stored in the RAM on a Cisco switch or router?

Answer 2

Random Access Memory

• running config
• arp cache
• routing table
• packet buffer

These are all things that tend to change quickly, and if the device is restarted they’ll be erased.

Question 3

What does ROM stand for? What is stored on ROM/what processes is ROM responsible for?

Answer 3

Read-Only Memory

POST (Power On Self Test)
Bootstrap
Mini-ios
ROMMON

Question 4

Identify the sequence of operations when a device boots up.

Answer 4

• POST (tests stuff…)
• Bootstrap searches for ios image in flash (if image not present, device will search a designated tftp server for image. If no designated tftp server, an ISR will broadcast trying to locate tftp server), then, if that fails, checks ROM and finds the mini-ios. If this happens, you’re basically in ROMMON mode.
• IOS checks registry value and determines whether to seek a startup configuration. If yes, searches NVRAM for a config file.
• If startup config is found, the device loads it. If not, it enters setup mode.

Question 5

What is the default registry setting? What is the setting for password recovery?

Answer 5

0x2102

0x2142