I am slightly confused between DNS and Name server. Are they the same thing or is there a difference between two?
There is no such thing as a Domain Name Server.
DNS stands for Domain Name System, which is simply a hierarchy of Name Servers that has the intent to translate host names into IP addresses on a global scale. A name server hosts or caches these translations, in the case where they are hosted the name server is often called a DNS Server.
Counting all name servers is a bit tricky, because you can't simply enumerate all the domains.
Let me give you an example on resolving
superuser.com in a non-cached way:
The name server that I use is
This is my local router which caches DNS entries, it has a Hosts file to reroute malicious domains.
The router has the name servers
18.104.22.168set, known as Google DNS, they also cache.
Google DNS will contact authoritative root name servers, which are the top of the DNS hierarchy.
Google DNS will contact the
.comname servers, the IP of which it received from the ARNs.
Google DNS will contact the DNS server for
superuser.com, of which IP it received from
A simply whois reveals:
NS1.SERVERFAULT.COM NS2.SERVERFAULT.COM NS3.SERVERFAULT.COM
The IPs for these name servers are known as they are registered at the
.comname server, when you register a new domain you always have to fill in the DNS servers that you use along their IP.
Google DNS will contact the DNS servers of
superuser.comto find the IP of
nslookup superuser.com NS1.SERVERFAULT.COM Server: NS1.SERVERFAULT.COM Address: 22.214.171.124 Name: superuser.com Address: 126.96.36.199
The term name servers are also used in different contexts, read Spiff's answer for more.
A DNS Server typically is for converting FQDN (www.xxx.com) to IP Addresses (192.168.0.1).
(A DNS Server also does a lot more, it can perform reverse lookups, and in recent years does a lot of other tasks with text tags, geo-ip and a lot more).
On the other hand, "Name Server" is typically used to locate a DNS Server.
For example, On a Whois record, a Name Server is typically the address for the DNS server that hosts the records for that domain.
A further more complicated example is, if you queried
www.superuser.com, you would go to your dns server and a recursive DNS lookup would occur on the superuser's nameserver.
As for how many are there - how long is a piece of string! This is an impossible question to answer... As a guess, I would put it in to the hundreds of thousands, if not low millions (for publicly accessible DNS Servers).
In some contexts, the term "name server" can refer to servers that aren't part of the Internet Domain Name System. For example, a WINS server is a name server for Microsoft's legacy proprietary networking protocols. There may have been other legacy LAN systems that had their own types of name servers that weren't part of Internet DNS.
The acronym DNS means Domain Name System. It is a distributed system for translating host names (and other data) to IP addresses in a large scale (world). The
name server is usually what people call the local DNS server that a workstation/PC can use as its entry point into the DNS. It will resolve local names, but delegates to other names servers for those it can't answer.
There are many name servers, but you don't need to know how many since they are queried as needed. There are only a few "root" name servers (the DNS is hierarchical).
DNS is Domain Name System and there is nothing like Domain Name Server!
The Domain Name System (DNS) is a hierarchical distributed naming system for computers, services, or any resource connected to the Internet or a private network. It associates various information with domain names assigned to each of the participating entities. Most prominently, it translates easily memorized domain names to the numerical IP addresses needed for the purpose of locating computer services and devices worldwide.
A DNS has a lot of DNS record types like
- A : Returns a 32-bit IPv4 address, most commonly used to map hostnames to an IP address of the host
- AAAA : Returns a 128-bit IPv6 address, most commonly used to map hostnames to an IP address of the host.
- MX : Maps a domain name to a list of message transfer agents for that domain and many more... One of them is also
- NS(Name Server) : Delegates a DNS zone to use the given authoritative name servers
Note : As of February 2013, there are 13 root name servers specified, with names in the form letter.root-servers.net, where letter ranges from A to M(though they exist in more than 13 physical locations). Here is the list.