Why is there no security token in my survey's URL?
In August 2012 and later releases, we added a security token into a survey's URL to prevent someone from changing the survey_id in the URL and loading other surveys from the site. This indicates every survey should not be accessed without a security token in the URL.
If a survey is identified with no security token, it is likely that survey was created in a version prior to August 2012. This is to ensure that any survey created in prior releases would still load (without the security token). This prevents broken links that may have been published (or exist in emails sent to contacts).
Whether or not it is required depends on the survey's created date.