Answer Description

Networking equipment typically ships with a default password or no password at all. Changing the password should be step one, before any other configurations.

Wikipedia

Where a device needs a username and/or password to log in, a default password is usually provided to access the device during its initial setup, or after resetting to factory defaults. Manufacturers of such equipment typically use a simple password, such as admin or password on all equipment they ship, expecting users to change the password during configuration. The default username and password are usually found in the instruction manual (common for all devices) or on the device itself. Default passwords are one of the major contributing factors to large-scale compromises of home routers. Leaving such a password on devices available to the public is a major security risk.Some devices (such as wireless routers) will have unique default router usernames and passwords printed on a sticker, which is more secure than a common default password. Some vendors will however derive the password from the device's MAC address using a known algorithm, in which case the password can also be easily reproduced by attackers.