OK, let me try to explain one more time. Sorry for this long post.
1 - the more useful link is definitely this
one. Be sure to understand and apply what it explains.
2 - if you want to be sure that users are using proxy, your FW should
NOT contain any "allow any to any" rule (it looks so obvious to me
)
3 - referring to this
link, DNS based advertisement has wider coverage than DHCP.
4 - your are currently facing issues that are not due to DNS implementation but to wrong wpad.dat file, or at least you don't know because you have not been able (or wiling) to validate this step.
So I will explain again (last time perhaps) how to proceed, step by step.
1 - configure your Zentyal proxy as explicit proxy. Do not set filtering rules, profiling, authentication or whatever, only simple "non transparent" proxy.
2 - configure your browser to use this proxy and ensure it works (feel free to remove any "allow any to any rule in your FW
)
3 - once (and only once) this works, configure web server and wpad.dat file so that you get access to proxy when proxy is not explicitly configured in your browser but when you are using URL to point to web server exposing your wpad.dat file (this must be something like
http://wpad.yourdomain/4 - once above works (and only once it works
) you can start working at DNS level to expose A and SRV records. If you're not happy with DNS, you can go with DHCP. In any case, as you can see, this is the very last step, only everything above works.
I hope I'm crystal clear now. If not, just tell me