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DNS Server in DHCP options keeps changing to Sophos IP

Rog163

Hi All...

Customer has XG135 (SFOS 19.5.3 MR-3-Build652), Sophos is the main DHCP server for the network, for the last few months we have been battling with a strange issue.

Sophos LAN IP is 172.16.0.10

Internal Microsoft DNS server 172.16.0.1.

DHCP on the Sophos is configured to use 172.16.0.1 for the DNS, Randomly the Sophos will change the DNS server to itself (172.16.0.10) - Causing DHCP clients to get 172.16.0.10 DNS which then causes issues with internal DNS resolution.

Multiple support tickets opened with support- the keep wanting to read logs and to tell them when it happens- no actual help to resolve this.

Customer does have multiple static reservations configured on Sophos DHCP.

Anyone had this issue before or have any suggestions?



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  • 0

    To add to this, we find if after adding a reservation to the DHCP, We double check the DNS is correct (172.16.0.1), Click Save and go back into the DHCP settings and the DNS Server changed to the Sphos IP (172.16.0.10), we then have to set it to 172.16.0.1 again and click save. 

  • +1 in reply to Rog163

    Hi Roger Da Camara 

    Try to set DNS1 as 172.16.0.1  on DNS settings as below and then tick mark Use device's DNS settings under DHCP or untick Use device's DNS settings and set your DNS IP on DHCP server might help to fix the issue.

    Regards

    "Sophos Partner: Networkkings Pvt Ltd".

    If a post solves your question please use the 'Verify Answer' button.

  • 0 in reply to Bharat J

    Hi Bharat...

    see below how its currently configured, I currently have DNS configuration configured to 8.8.8.8 and 1.1.1.1 for Internet DNS resolution. Chaning it to internal IP would break DNS Resolution for internet?

     

  • 0 in reply to Bharat J

    Hi Bharat...

    I have applied changes you suggested yesterday - i will monitor over the next few days and see if i still have any issues with The DNS setting under DHCP changing. Thanks for the help once again

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