The "No Referral" entry in the Urchin Referral report is typically a combination of the following type of traffic:
Direct Address:
If a visitor types your website address into an explorer
address bar, there will not be any referral information
passed to the web server. Every file request -or "hit"- to
a web server is logged in a file, and each entry has a
referral field which may or may not contain data. When an
address is accessed manually as described above, no
information is recorded in the referral field because the
visitor was not referred by a link on another site.
Email link:
When a visitor clicks a link in an email message (such as an
email advertising campaign) there may not be any referral
information passed. It is possible to create email links
that pass referral information to the web server the site
resides on. But, this must be setup by the individual that
creates the email content.
Web spiders:
Robots crawlers and spiders spawned by search engines
usually account for the majority of "No Referral" hits.
these are all programs that visit Web sites and read their
pages and other information in order to create entries for a
search engine index.
Internal Referrals:
Urchin does not include any internal referrals in its
reports if they are configured correctly. An internal
referral is a referral from the same website that the first
requested page belongs to. If an internal referral is
discovered in the referral field, it will be included in the
report as a "No Referral" hit. It is uncommon for an
internal referral to appear in the initial request for a web
page. But, there is one specific circumstance in which such
referrals are common.
Many large ISPs and Search Engine sites use cache servers to capture web site content. By doing so, they can reduce the time and network traffic necessary to serve these pages to visitors faster. But, when a visitor requests your web page and a cache server responds to that request, your web server log has no knowledge of that request. As a result, your web server log file will not contain any information about the request either. The net result of this action is that a new visitor will often not be seen by your web server until a second or third page request is made. By that time, the pages he or she requests will be accessed from links on other pages on your web site. Therefore, the referral field in the log file will display your own pages as the referral. This results in the internal referral hits that urchin adds to the "No Referral" report.
Unless you are able to keep all of your web pages from being cached remotely, there is nothing you can do to remedy this situation with the Urchin 3 product. However, both Urchin 4 and Urchin 5 can reclaim the missing log file data if you configure the Urchin Traffic Monitor (UTM). More information about the UTM is available from our documentation center under the "Visitor Tracking" menu.