DNS Redundancy

[lost]

Hell all,
could someone please explain what all this fuss about dns redundancy is about?
Everywhere I go I hear that dns servers should be geographically seperate, they should be on different class c networks, some companies advertise that if I use their dns for my domain it will ALWAYS be available.
All this sounds like hog poopoo to me.
Currently i have my dns on the same box as my domains A record. If my server goes down, yes, noone can find my domain. If I had my dns servers elsewhere and my box craps, how will the 'outsourced' dns magically connect visitors to my domain if my A record is not pingable?
Am I way off here with logic or am I missing something?

Cheers,
L

[henker]

Have you taken mail into account ? If all your DNS servers are on one box and that server goes down - well...