If, like me, you want a dedicated IP, then DHCP is not the best option unless you have a router that allows you to set reservations.
What often happend with some E2 images is that after you set them up and do a restart they forget the DNS settings which gives the error you describe. I am still at a loss as to why this happens. I bet if you went into the settings both DNS settings would be wrong or even 0.0.0.0
You can either put the DNS addresses in, in full or just enter your router IP address as the first entry so the STB uses the router's settting. I normally use the router IP coz I'm too lazy to input both addresses. lol
In the /etc folder there is a file called resolv.conf. The entry in the existing one looks like this "resolv_conf=/var/run/resolv.conf". This leads one via a link to an area which is lost after a restart so may be the reason why it forgets the settings. In effect it will mean readding every time you do a restart.
I delete the file from /etc and replace it with one that contains my nameservers which looks like this "nameserver 192.168.1.1"