Proxy should have nothing to do with binding to AD. DNS and time server settings are the two biggies you need to make sure are correct when binding.
Also when you are running the imaging tool are you doing it from 10.9.x box? there are/were some bugs in installer on 10.9.x that did not deal real good with 10.10 OS and saw it as 10.1
I could potentially see this issue, if you were using JDS to host your payloads, since it pulls those down via WebDAV, and making requests through the proxy instead of going directly to the server. You can try to manually set the proxy bypass, and if that works, examine your Proxy Autoconfig.
Try adding an exception domain to your proxy list. For example from the command line on the Ethernet adapter.
#!/bin/sh
networksetup -setproxybypassdomains "Ethernet" "*.local" "169.254/16" "*.corp.com"
We do indeed host payloads on the JDS and do pull down via WebDav I will add the JDS server to our proxy exceptions list.
I run two scripts before 'imaging' the OS, the first sets the time server and the second the proxy set up and bypass.
The proxy bypass has grown, during the lifetime of Maverick one of the Maverick patches meant we could not use wildcards or a range of IP's - it would only work with absolute values so we added them alongside the wildcard and range settings because we could not be sure when a patch would revert it.
One of the later patches to Maverick stopped the use of the PAC file and it has never worked for us with Yosemite (though there have been some significant changes onsite - switch to VLan and all services and shares moved to virtual which may have had some impact though all virtual servers retained the same dns names and IP's)
Cheers
Phil
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systemsetup -setnetworktimeserver ourtimeserverX2.uk.xxx.com
networksetup -setproxyautodiscovery Ethernet on
networksetup -setautoproxystate Ethernet off
networksetup -setproxybypassdomains Ethernet .local, .uk.XXX.com, ftp.uk.XXX.com, autodiscover.XXX.com, 1X.XXX.X., localhost, 1X.X.XXX., 1X.X.126.15X, 1X.XXX.1.33, XXXXX1.uk.XXX.com, 1X.XXX.2.41, 1X.XXX.2.43, 1X.XXX.2.45, 1X.XXX.2.47, 1X.XXX.2.49, 1X.XXX.2.52, 1X.XXX.2.56, 1X.XXX.2.48, 1X.XXX.2.88, *.XXX.com
speaking of AD and PAC / Auto Proxy
If you have access to the L-Cap beta's you might want to test in your environment
http://openradar.appspot.com/radar?id=6631169592393728