To find out the DNS server IP address used by your router, you can log into the router's web-based configuration page and check the network settings.
To do this, follow these steps:
Connect to your router's Wi-Fi network or connect a device to one of the router's LAN ports using an Ethernet cable.
Open a web browser and enter the router's IP address in the address bar. The IP address of the router is usually listed in the documentation that came with the router or on the bottom or back of the router itself.
Enter the router's login credentials when prompted. The login credentials are usually listed in the documentation that came with the router or on the bottom or back of the router itself.
Navigate to the network settings page or the DHCP client list page. This page may be labeled differently depending on your router, but it should be located under a menu such as "Network," "LAN," "Internet," or "WAN."
On the network settings page or the DHCP client list page, look for a field labeled "DNS server" or "Primary DNS server." This field should contain the IP address of the DNS server used by your router.
If you are unable to access the router's web-based configuration page, you can use the nslookup command to find out the DNS server IP address used by your system. This command allows you to query the DNS server to resolve a domain name to an IP address.
To find out the DNS server IP address used by your system, run the nslookup command with the google.com domain as an argument. The syntax is as follows:
nslookup