If you don't know the DNS server, you can use the same settings as the Default Gateway.
4.4.2 DDNS
FOSCAM camera has embedded a unique DDNS domain name when producing, and you can directly use the
domain name, you can also use the third party domain name.
FOSCAM Domain Name
Here take cp4911.myfoscam.org for example. Go to option of DDNS on the Settings >Network panel, you
can see the domain name.
Now you can use http:// Domain name + HTTP Port to access the camera via internet.
Take hostname cp4911.myfoscam.org and HTTP Port no. 8000 for example, the accessing link of the camera