dns setting for client

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dns setting for client

Julie Xu

Hi,

 

We have changed DNS server, and on dhcpd.conf I did change the dns to new server, but, on the client site, if you do ipconfig/all, you can see the dns is still pointed older dns server, if there is possible to on dhcpd.conf to force dns server change?

 

Any comments will be appreciated

 

Thanks in advance

 

Julie


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Re: dns setting for client

Pankaj Mishra
set your dns server manually or renew the IP lease.

-Pankaj

On Thu, Oct 3, 2019 at 3:47 PM Julie Xu <[hidden email]> wrote:

Hi,

 

We have changed DNS server, and on dhcpd.conf I did change the dns to new server, but, on the client site, if you do ipconfig/all, you can see the dns is still pointed older dns server, if there is possible to on dhcpd.conf to force dns server change?

 

Any comments will be appreciated

 

Thanks in advance

 

Julie

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regards
-Pankaj!

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RE: dns setting for client

Julie Xu

Hi, Pankaj, and others

 

Is it possible on dhcpd.conf to inform client doing renew?

 

Manually change dns server or use “ipconfig/renew” to change dns is not possible at my case.

 

Any comments will be appreciated

 

Thanks in advance

 

Julie

 

From: dhcp-users [mailto:[hidden email]] On Behalf Of Pankaj Mishra
Sent: Friday, 4 October 2019 10:12 AM
To: Users of ISC DHCP <[hidden email]>
Subject: Re: dns setting for client

 

set your dns server manually or renew the IP lease.

 

-Pankaj

 

On Thu, Oct 3, 2019 at 3:47 PM Julie Xu <[hidden email]> wrote:

Hi,

 

We have changed DNS server, and on dhcpd.conf I did change the dns to new server, but, on the client site, if you do ipconfig/all, you can see the dns is still pointed older dns server, if there is possible to on dhcpd.conf to force dns server change?

 

Any comments will be appreciated

 

Thanks in advance

 

Julie

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dhcp-users mailing list
[hidden email]
https://lists.isc.org/mailman/listinfo/dhcp-users


 

--

regards
-Pankaj!


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Re: dns setting for client

Simon Hobson
In reply to this post by Julie Xu
Julie Xu <[hidden email]> wrote:

>We have changed DNS server, and on dhcpd.conf I did change the dns to
>new server, but, on the client site, if you do ipconfig/all, you can
>see the dns is still pointed older dns server, if there is possible to
>on dhcpd.conf to force dns server change?

As soon as you have updated the server, it will start serving the new information. However, it's a pull transfer and relies on the client to ask for it. By the end of your max-lease-time setting, you can guarantee that there are no active leases that we're given with the old settings.

However, I vaguely recall some discussion in the past related to clients that didn't update settings when renewing an active lease. I don't know whether your clients fall into that group.

As already said, manually releasing and then renewing the lease at the client end should do it. Or just wait...

A brute force method would be to change your IP range and force clients to get a new lease. Add a new range, set the old one to "deny booting", and then tne server will Nack any renewal requests for the old addresses.  This will break all existing connections.
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