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JamesEdmonds-7766 asked JamesEdmonds-7766 commented

DNS issues with RRAS clients with two static address ranges

Hello,

We have a 2012 R2 RRAS server providing VPN access to remote clients.
It uses a static pool of addresses from 10.0.0.50 to 10.0.0.80

We needed to free up two addresses from the middle of the pool of 10.0.0.65 and .66
We therefore reduced the static pool range to 10.0.0.50 to 10.0.0.64
We then added another pool of 10.0.0.67 to 10.0.0.80, so it looked like this:
136928-image.png

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 10.0.1.10 and 10.0.1.11)
Our network is a /23 so it's 10.0.0.0 netmask of 255.255.254.0

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 10.0.0.51 which is essentially in the same pool it was before.

Thanks
James


windows-server-2012windows-server-infrastructurewindows-platform-network
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JamesEdmonds-7766 answered

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.

Thanks
James

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LimitlessTechnology-2700 answered JamesEdmonds-7766 commented
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Hi,

Whilst in the future when I rebuild the server on new infrastructure, we will be using DHCP relay, we aren't using it at the moment.
The IP addresses are assigned from a static pool assigned within RRAS.

We know the settings are ok and it's unlikely a subnet issue, as normally there is absolutely no issues.

As per my own answer to this question, I think the issue was affected clients were being assigned an address from the pool already assigned to another device on the network, causing routing issues.
All I need to know now is if my approach to excluding addresses from the pool is valid, and I will exclude that particular address from being distributed in future.

Thanks
James

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Is my method of excluding addresses from the local pool correct, by shrinking the range and then adding another range starting after the IPs I want to exclude?

Thanks
James

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