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Set IPv4/6 Adapter Metric, Windows 7/10 DNS issue

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#1 Stefan Werner

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Posted 27 February 2017 - 04:34 AM

Hello folks,

 

first off TL;DR:
Windows assigns metrics automatically, when a connection is faster than the virtual VPN Adapter's stated speed, you don't get DNS resolution for internal networks.

 

 

We had DNS issues for several customers that boiled down to the virtual NAC VPN adapter metric.

Basically, this metric is used for DNS requests in Windows 7/10 and we had to change it to a value that would make sure the NAC VPN adapter is always preferred when a VPN connection is established. Otherwise, connections faster than 100mbit/s (NAC VPN adapter speed) would get used to resolve DNS and thus our users local Modem/Router would try to resolve company internal hostnames using external DNS servers. I specifically refer to the adapter metrics for IPv4 and IPv6 Interfaces on the NAC VPN Adapter, not to any routes.

Number of cases seems to increase because of home office users' wifi connections, as well as notebooks' wifi adapters, getting faster. We had one out of >1000 users connecting over LAN from home, same issue.

 

So my feature request: Add a switch for NAC client installation to set the metric value for the NAC VPN adapter. Maybe even set a default value of 1 or 2 for the metric.

Thanks

Kind regards,
Stefan Werner



#2 Alexander Heiss

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Posted 27 February 2017 - 10:10 AM

We had the same problem and there is already a solution.

Go to the Barracuda VPN Client Options (Barracuda VPN Control) -> Advanced (Left side or under View) -> Automatically prioritize VPN adapter = Yes

 

When the Barracuda VPN Client now makes a new connection it will sort his VPN adapter on First Position, with that Windows will use the internal DNS server.

We set this as via a GPO (regedit value).

 

Hope this helps.



#3 Stefan Werner

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Posted 28 February 2017 - 05:55 AM

This doesn't change the metrics responsible for DNS resolution, just tested and reproduced the error to make sure I didn't get it wrong.

Besides, network adapter binding order is no longer used in Windows 10, see https://blogs.technet.microsoft.com/networking/2015/08/14/adjusting-the-network-protocol-bindings-in-windows-10/



#4 Stefan Werner

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Posted 02 March 2017 - 07:11 AM

Moved the request over to the "New Idea Portal"