SonicWall setup issue: Connection Failure DNS lookup failed, please check your DNS server settings

Posted on 2014-08-31
Last Modified: 2014-09-02
Dear Experts,

I have an issue with my sonicwall tz series. I've completed wizard setup and upgrade with the latest firemware. Somehow after the setup, I don't have an internet connection.

1. I've checked the connection x0(lan) and x1(wan) and when I log into the sonicwall from the login page, I can see that x0 and x1 have signal with 100Mb connection.

when I want to register my sonicwall from one of the link, I got the 'Connection failure' error. It says that 'DNS lookup failed, please check your DNS server settings'.

I am using a cable modem and during the initial setup guided by the wizard, I choose the cable/modem configuration.

Is there something that I've not configured correctly? Thanks
Question by:Kinderly Wade
    1 Comment
    LVL 15

    Accepted Solution

    Assuming that the Sonicwall is providing DNS and DHCP for your LAN, try pinging from one of the computers. If you get no replies then you've a bigger problem than just DNS.
    If you run ipconfig /all on the computer that will tell you what DNS servers addresses are being supplied via your DHCP server.

    If you do get replies then check the Sonicwall to see what DNS settings it's actually using. Normally the ISP's DNS servers will be published to your router via the ISP's DHCP assignment of your public IP address, but you may have to enter them manually in the appropriate fields. If you have trouble finding your ISP's DNS server IP addresses you can use Google's public DNS server addresses ( and instead, until such time as you discover the former.

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