My hosting companys two nameservers are on the same IP block, which I believe is a problem. My domain registrar offers "Secondary DNS", but I don't really understand their explanation on what it is. Does Secondary DNS just copy the records from the other nameservers? Is it a good idea/safe/recomended to use it? Thank you!
Secondary DNS is useful if your primary dns server went down or too busy to serve request
Thanks for your replies, the above is what I'm interested in. How does this system work exactly? Say I have three nameservers, two from my host and one from my domain provider (secondary DNS). If my host's two servers are unreachable does that mean that browsers will try each one in turn, from 1 to 3, and take the first one that replies? Or do they check any at random?. If one fails, do they try another on the list?
It all depends upon os and local resolver configuration. In simple term, browser will try to check all name server before returning domain not found error. It is good idea to have secondary name server outside your data center or country.