How to prevent duplicate or fraudulent responses in a survey
A public survey with no protection at all is vulnerable to two different problems: someone submitting the same response multiple times (on purpose or by accident, reloading the page), and automated volume — a script or bot sending dozens of responses per minute to inflate or skew a result.
Why not the obvious fix (login or captcha)
Requiring a login solves the duplicate problem, but kills the response rate and breaks any anonymity promise. A captcha adds friction to every legitimate response to stop a volume of bots that, for most surveys, isn't even the main risk. Both fixes solve the problem at the cost of making the experience worse for everyone answering in good faith.
How SurvIQ handles it: a silent, per-IP limit
SurvIQ limits how many responses the same IP address can submit within a short time window, with no login and no challenge shown to the respondent. The limit is generous enough not to affect someone answering normally (even if they correct and resubmit once), but it cuts off the volume pattern that characterizes an automated attack.
Why it's per IP, not per survey
The limit applies per IP address, not per specific survey. A large survey can receive thousands of legitimate responses from different IPs with no issue between them — what gets limited is the same IP sending an abnormal volume, regardless of which survey it's hitting.
What this doesn't cover
This protection stops automated volume and accidental resubmissions, but it doesn't stop a motivated person from answering multiple times across different networks (wifi, mobile data, another location) if they're determined to. For surveys where the exact identity of the respondent matters (tracked panels, for example), the real protection comes from distributing through personalized per-contact links, not from the IP limit.
When to worry about this
For most internal or low-visibility surveys, this already works without the survey owner configuring anything. It's worth paying closer attention when the survey is shared on a very public channel (social media, an incentivized giveaway) — that's where automated volume or prize-motivated resubmissions become more likely.