In other words the IP(s) of where your TKL appliance will get it's DNS from. You need to specify at least one. If you are running a local DNS server then use the IP of that, if not, then often consumer grade modems do a DNS passthrough (i.e. you set the DNS provider in your router then all other connected computers use the IP of your router as the DNS/nameserver IP), or you can use an external DNS provider (assuming that your appliance has internet connection). Generally your ISP will provide a DNS service although in my experience they are usually sub-optimal. Like I said above, I'd recommend using google's public DNS: 8.8.8.8
You need to enter the IP of a nameserver
In other words the IP(s) of where your TKL appliance will get it's DNS from. You need to specify at least one. If you are running a local DNS server then use the IP of that, if not, then often consumer grade modems do a DNS passthrough (i.e. you set the DNS provider in your router then all other connected computers use the IP of your router as the DNS/nameserver IP), or you can use an external DNS provider (assuming that your appliance has internet connection). Generally your ISP will provide a DNS service although in my experience they are usually sub-optimal. Like I said above, I'd recommend using google's public DNS: 8.8.8.8