Previously the devices have looked in multiple locations that are derived from its configured DNS domain, going upwards in the domain tree until it reaches the top-level domain.
We have removed upwards domain search and now the devices attempt to download from a single location: http://wpad/wpad.dat . Note the unqualified domain name, meaning the default DNS search domains is used in the lookup.
This behavior matches the way how WPAD support in web browsers, such as Netscape and Firefox, works.
If you’re using this functionality, do one of the following:
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Put the WPAD server into the DHCP reply, allowing the clients to skip the DNS search altogether.
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Make sure the domain name containing the WPAD host is in the DNS search path of the clients using either DHCP or xConfiguration Network 1 DNS Domain Name.
Resources for more information on WPAD:
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WPAD, Wikipedia: https://en.wikipedia.org/wiki/Web_Proxy_Auto-Discovery_Protocol
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Functionality in Netscape/Firefox: https://bugzilla.mozilla.org/show_bug.cgi?id=1552105#c6