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Server 2016 - DHCP BPA error - The IPv4 addresses of the DNS server should be reachable.

Question

Monday, November 18, 2019 1:48 PM

Good day folks

Got this error in my one DC dashboard. It is my PDC and on-prem with another DC.

The NIC's have static IP's and primary entries are looking at each other, secondary entries are loopback addresses (127.0.0.1).

I'm not sure where to look as even the link doesn't clarify the matter to resolve it. I am looking to remove it from BPA due to resolution, not to hide the message :)

Thanks for your help.

Kindest regards

Darren

All replies (9)

Wednesday, November 20, 2019 8:54 AM âś…Answered

Hi Darren ,

>>The error doesn't tell me which IP address or DNS server is unreachable, and I don't know how to pin it down.

Use nslooup command to check whether the DNS server is reachable from client computers.

If the resolver returns the IP address of the client, the DNS server does not have any problems.

For your reference:

Troubleshooting DNS servers

If the resolution is fine, I would suspect this DHCP BPA result is related with DNS forwarders, as we discussed in this thread

Remove the unresponsive forwarder and then check if DHCP BPA still occurs any error messages.

Best Regards,

Candy

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Tuesday, November 19, 2019 2:55 AM

Hi ,

>>The IPv4 addresses of the DNS server should be reachable.

The error is related with DNS configuration.

Please first check the DNS address configured for the scope is right.

Here is the reference for the error:

DHCP: The IPv4 addresses of the DNS server should be reachable

Best Regards,

Candy

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Tuesday, November 19, 2019 6:21 AM

Hi there Candy

Thanks for the reply.

I have taken a look at that article before, I could not see any assistance from it as it's referring to IPv6 for an IPv4 issue. I checked its steps (we don't have IPv6 set up and environment does not support it), and there are no such options as laid out there. There is no 006 DNS option, only various IPv6 specific options like recursive, SIP settings etc.

I've checked every scope (we have multiple scopes and super scopes) for the DNS servers option, and every one has at the very least the DC (it is also a DNS server) and the other partner DC (also a DNS server) listed in amongst the DNS servers. The error doesn't tell me which IP address or DNS server is unreachable, and I don't know how to pin it down.

Kindest regards

Darren


Monday, November 25, 2019 1:54 AM

Hi Darren,

Did you have any updates on this issue?

Best Regards,

Candy

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Monday, November 25, 2019 6:18 AM

Good morning Candy

I am just waiting to get verified still so I can upload that screenshot to you for the DNS forwarders thread, and once we sort that, then I can update if the DHCP error disappears.

Kindest regards

Darren


Monday, November 25, 2019 10:51 AM

Hi there Candy

Thank you very much for your help!

The BPA error was resolved after following your steps as per this thread.

I really appreciate your help! Thank you!

Kindest regards

Darren


Tuesday, November 26, 2019 1:24 AM

Hi ,

You are welcome!

Best Regards,

Candy

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Tuesday, November 26, 2019 11:19 AM

Hi there Candy

Back again for my same server! Some more dreaded BPA results have cropped up after a brief respite when this was resolved.

The following never came up before, but now are?


Thursday, November 28, 2019 1:45 AM

Hi ,

Sorry for the delayed response.

Since it involves some new error message, could you please open a new thread on this topic?  

I will try my best to assist you on the new thread.

Your kind understanding is appreciated. 

Best Regards,

Candy

Please remember to mark the replies as an answers if they help.
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