* Some browsers won't send a referral string: * Most browsers won't send a referrer when: * Some browsers will generate false referrers when: * Dynamic Content * favicon.ico
Summary from this thread:
-- An unsupported or optional feature. Many browsers have options to turn off referral string generation as a security precaution.
-- When "open this link in a new window" is selected in the browser.
-- if security settings are high.
-- if using a proxy server or other filtering agent.
-- if it is a secure page. Some browsers won't send an external referral string as a security precaution.
-- a bookmark is selected,
-- the url is typed into the address bar,
-- some other program launches the url (such as email or news).
-- if the user has your page set as their homepage
-- from some local file based link (viewing a disk based html file).
-- from page links dragged to the address bar on browsers that support it.
-- they are located on an isp with a proxy cache. This could mean people from that isp are being vastly under counted.
-- if they are on a isp that has a proxy cacher and that proxy cacher is set to rerequest pages with unique referrers. The rest of the pages that have identicle referrers to the previous cached document, will come out of the isp cache. They could view 50 pages and you only show 10 in your logs with unique referrers.
-- browser caching. Some browsers will repeatidly send the initial external referrer to every page it visits on a site.
-- cache validation. Some browsers send a referrer with "If modified since" requests or even simple "head" checks.
-- reloads. If the page is reloaded, referrer may be that very page or the original referrer to that page.
-- Many sites are mixes of dynamic and static content. Most dynamic documents are not cacheable (cgi based urls). Thus, they can skew referral data dramatically.
-- No longer valid to use for detecting bookmarking of your site. Mozilla, Netscape, and Opera can request the file at every visit to every page depending on settings. That completely skews the data now.
* Some browsers won't send a referral string:
* Most browsers won't send a referrer when:
* Some browsers will generate false referrers when:
* Dynamic Content