sorry there is still a silly question remaining,
the difference between the DNS of Frihost/(webspace provider) and Opendns/Google DNS(184.108.40.206,220.127.116.11)?
They are different, right?(considering the former one is always written in the form of ns(*).*** while the later in the form of IP)
Any relation between them?(They are both called "DNS")
I did a search but there seem to be nobody asking this question,is it too silly to be asked?
short answer: one is to tell the world what is the IP address of your domain, the other is to tell you, what the IP address of other people's domain.
long answer: you know the crap about people are bad with numbers and how they create dns system, etc? no? wiki is your friend and how's stuff work also have good explanation for children under 12 to understand. once you know the history, you can continue reading.
now your computer need to resolve the IP address of certain domain. to start, your computer need a service called DNS server to do that. and since this is the first step, without which, you can never resolved a domain to IP, you definitely cannot use a domain name as your computer's DNS server because then it will have no way to resolve it (unless you put the domain/IP pair in your host file, which is another story for another day), so you need to use IP as your computer's DNS server. kind like what Slevin told Elvis not to use the word your defining in the definition in Lucky Number Slevin.
you got that part? you need to have DNS server to resolve a domain name, and if your DNS server itself is express as a domain name, you computer will have problem because it need to resolve the domain of your DNS server even before you can use it. so you use IP. call this DNS_1.
now that your computer have somebody to refer to when it want to resolve a domain name, the question is: is your DNS server keep track of everybody's domain-IP thingy? like google.com is x.x.x.x, yahoo.com is y.y.y.y, and so on. everyday, thousands upon thousands new domains are created. your DNS server's admin got better thing to do instead of keeping track of domain registration. on top of that, IP address of each domain keep changing. my house which use dynamic IP from my ISP, yet has a domain pointing to it using no-ip service will have it's IP change every time it connect to the Internet. no way in hell your DNS server admin will keep track of it. so who does?
the answer: the owner of the domain need to announce to the world what is the IP of their domain. how they do that? by using another kind of dns server, which instead of resolving a domain to IP, it tell the world the IP of a domain. call this DNS_2.
so your computer will ask DNS_1 what's the IP of a certain domain is, DNS_1 will ask some powerful servers called root servers. these root servers is so powerful it can lookup who own that domain (called the registrar) so fast, and it will then ask the registrar what's the DNS_2 of the domain, then it will ask DNS_2 what's the IP of the domain. the information will be pass back to DNS_1 and DNS_1 will pass the information to your computer.
so know you know the different between these 2 DNS servers and why DNS_1 need to be express in IP instead of domain.
btw, I don't believe in stupid question. you should too. if you don't know it, just ask.
The Google DNS servers, the OpenDNS servers, and your ISP's DNS servers that you use for lookups by default are all "recursive DNS servers". That means that in principal, they start at the root DNS servers and ask what nameserver is responsible for a given domain. They will follow a tree structure of servers, each of which chooses a subset of the names it knows about, and returns the address of the server which knows about that subset. Finally, a nameserver is reached which does not choose a nameserver but is able to directly return the ip address and other information about the specific domain asked for. In reality, the answers are cached to save most of the lookups but the result should be the same except the answer is returned faster.
The Frihost nameservers are the last ones reached; a leaf node of the tree; which knows all the information about the sites hosted here.