how is 4ch spam protected?

short question: how do you protect your board from automated bot spamming? i cant see any captcha! normally, from my expirience, a board  would  be instantly spammed to death without captcha or such protective measures. but 4ch board seems to be free of those problems... how do you do that ?

Captchas are a stupid way to prevent spam.
If spammers can't be bothered to circumvent dummy fields, why would they try to circumvent captchas?

Like you say, captchas help slow flooding. Some of us other board admins don't live to moderate the boards. It's sink or swim, &c.

(also, proxies)