DNS issues with RRAS clients with two static address ranges

James Edmonds 811 Reputation points


We have a 2012 R2 RRAS server providing VPN access to remote clients.
It uses a static pool of addresses from to

We needed to free up two addresses from the middle of the pool of and .66
We therefore reduced the static pool range to to
We then added another pool of to, so it looked like this:

We then started getting emails from several VPN users saying they couldn't access internal resources, which after some diagnosing via ping tests etc seemed to be a DNS issue (DNS servers are and
Our network is a /23 so it's netmask of

Can anyone explain why DNS issues would arise by simply changing the IP pool size and adding another pool? Especially as some of those people with a problem were using an IP low in the pool such as which is essentially in the same pool it was before.


Windows Server 2012
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A Microsoft server operating system that supports enterprise-level management, data storage, applications, and communications.
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Windows: A family of Microsoft operating systems that run across personal computers, tablets, laptops, phones, internet of things devices, self-contained mixed reality headsets, large collaboration screens, and other devices.Network: A group of devices that communicate either wirelessly or via a physical connection.
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Windows Server: A family of Microsoft server operating systems that support enterprise-level management, data storage, applications, and communications.Infrastructure: A Microsoft solution area focused on providing organizations with a cloud solution that supports their real-world needs and meets evolving regulatory requirements.
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  1. James Edmonds 811 Reputation points

    I think the issue may be a sudden unexpected IP conflict with another device on the network. It's possible the few users reporting the issue were assigned the conflicting IP causing a problem.

    Is my method of adding ranges to RRAS correct? If so, I will split the range again, and exclude the conflicting IP to prevent future errors.


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