Outlook 'contacting the server information' message

After implementing pacfile solution for proxy, the encounter 'contacting the server information' message keep appearing when opening HTML in Outlook.
Internet browsing using Internet Explorer is very slow in loading too.

Manage to isolate it that it is due to constant DNS reverse lookup for each access and the root cause is a certain parameter in the pacfile.

Issue caused by: isInNet(host, "a.b.c.d") parameters.
article link
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The danger of IsInNet, isResolveable and dnsResolve forcing client DNS Lookups for every Query

Using isInNet(host, "a.b.c.d") can cause major chaos with your DNS infrastructure. This relatively innocuous looking function will force EVERY browser to perform a reverse DNS lookup on every unique hostname that it tries to contact that’s not already a simple IP address. This can rapidly have significant consequences, depending on how many workstations you have and how robust your DNS infrastructure is. This doesn’t necessary mean that you can’t use this function, but that you must do it carefully and understand the implications. See the "PAC File Tricks" section for one way that it can be used safely.

The function isResolvable and dnsResolve have very similar issues as the described above They forces a DNS query every time the PAC is parsed for every request. Be careful using this for the same reasons. If you have a problem that only one of these functions can solve, use it carefully. Ensure that you don’t do unrestricted lookups for all hosts. Use logic like "if the domain name is company.com and IsResolvable"

If you use these functions, unexpected behavior might result. For example, if you try to look up an invalid domain name it’s possible that there might be a 30+ second delay for the request as the client tries to resolve the name. It can also place a tremendous load on your company’s DNS infrastructure, so be careful of its capacity.

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Tools used for the troubleshooting: DNSQuerySniffer

download from http://www.nirsoft.net/utils/dns_query_sniffer.html

After removing the IsInNet proxy pac parameters, you will realise that the number of DNS query is reduced on the DNSQuerySniffer tool.

And the message has stop and Internet Explorer browsing is loading faster too.