Network/Wired - Security of Network Passwords

Security of Network Passwords


I know this can vary from company to company, but in general, what are standard practices concerning the handling the security of the passwords only the System Administrator knows? Things like the built in Windows "administrator" account, switches and routers, network resources and shares, AV apps, ISPs, off site spam filtering services, Exchange, MX and C name records, domain registrar, website, off site backup services, purchasing from vendors, wireless carrier accounts, etc.

I realize that there should be a fail-safe so that in the scenario of the one person who knows them getting struck by a meteor and the interruptions of daily business that would cause, but how is this typically done?

Thank you. Thank you very much.