Symptoms
When you use Internet Explorer 11 to browse websites that use a proxy PAC file, the browsing may delay. This is caused when Internet Explorer 11 sometimes queries for a domain name that begins with the "dummy" word.
Resolution
Update information
To resolve this problem, install the most recent cumulative security update for Internet Explorer. To do this, go to Microsoft Update. Additionally, see the technical information about the most recent cumulative security update for Internet Explorer.
Note This update was first included in March cumulative security update for Internet Explorer (MS15-018).
More information
This issue occurs because the cross-origin checks cannot accommodate the blob protocol that is used by web workers.
Status
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
References
See the terminology that Microsoft uses to describe software updates.
