There are many kinds of bans that NK/kong can throw on a user.
SAS 4 Edit
MP ban Edit
This is the lowest level of ban. Someone banned from MP will only see other MP banned players. Their event or champ scores are also permanently stuck at 0. This ban is put on most hackers.
ID ban Edit
A higher level of ban. A user's entire ID or username is banned. An account that has been ID banned will not get past the loading screen. There is no way around this. This ban is put on hackers with too many good hacks, or repeated ban evasion. This may be the new way to ban with the new hacks.
ninjakiwifiles.com IP ban Edit
In some ways the highest level of ban. If an IP is be banned from ninjakiwifiles.com, that user cannot play any games by NK. Even users on kong can be banned like this, but only on SAS 4 because the swf file is from there. If NK's games are hosted on the kong website you won't be banned. This is a measure against users who hack multiple games or accounts.
"Other" bans Edit
IP ban Edit
As said in the name, a user's IP will be banned from NK. They usually only last 2 weeks. Kong however cannot IP ban a user from the entire website.
Account ban Edit
An entire account is banned. An account suffering an account ban cannot be logged into. This usually is put on hackers who have AP earned illegitimately. For Kong, this happens when an account falls under these circumstances.
Commenting ban Edit
An account is banned from commenting on or creating forum posts/activity feed, likely due to the user posting profanity or spam. This usually lasts for about a month.
Unfair bans Edit
There have been multiple instances of unfair bans by NK.
Legit players MP banned from SAS4 and firstname.lastname@example.org not helping.