My site is being heavily attacked by spam bots and this is taking place only on one specific node. All other nodes are safe or the spam there is being blocked by Mollom. How do I prevent further spam comments from being posted over there? Do you have any idea?
If you don't care if nobody can comment on that node anymore, you could disable comments for that node. Go to the edit form and below "Comment settings" (assuming D6, slightly different in D7 but basically the same thing) change the value to "Read only" or "Disabled".
You could possibly
- disable comments for the given node, as mentioned by the previous user
- block by IP (link)
- install and enable CAPTCHA and it's "submodule", reCAPTCHA (the reCAPTCHA service is provided by Google), which effectively prevents spamming attacks when using forms (a spambot can't read the constantly changing texts with various forms).
Note: after enabling reCAPTCHA, you have to sign up for a free key here, and set the appropriate values on the admin page
- use Honeypot module, as suggested by @geerlingguy in his comment, which are "are effective against many spam bots, and are not as intrusive as CAPTCHAs or other methods" (quote from the module's page).