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Networking uses IP addresses to address different servers and clients on a network. However, most Internet users do not memorize and use the IP addresses for websites. Rather, they use domain names. These domain names are converted to IP addresses which are recognized by computers. This conversion is possible because of DNS servers. These DNS servers are important components of the Internet. This article will focus more on discussing the relationship between top-level domains (TLDs) and DNS servers as well as info on the Internet's DNS servers.
A list of USA domain servers and there information can be found at http://public-dns.tk/nameserver/us.html . The provided info includes IP address (version 4 and 6), hostname, physical location (city), DNS software, and reliability. For a list of all DNS servers world-wide, go to http://public-dns.tk/ . Near the bottom of the page is a list of country names that allow the user to view servers from a particular country.
If a DNS server's domain name or IP address is typed in a web browser's address bar, the browser will ask for a username and password. If the correct username and password is provided, then that user has access to a major component of the Internet's backbone.
If more info on a DNS server is needed, go to http://whatismyipaddress.com/ip/ and type the IP address. Then, information on the DNS server is presented.
FUN FACT: Google has two public DNS servers that are very reliable - 126.96.36.199 and 188.8.131.52.
The top-level domains (TLDs) such as ".com", ".net", ".org", etc. are managed by government agencies or corporations. For instance, Versign is an American company that manages and owns two of the thirteen Root-Servers. Verisign's DNS servers manage ".com", ".tv", and many other top-level domains. If a single Root-Server is hacked or crashes, the Internet is still usable. Also, if a DNS server is brought down, users can still access a website by typing the IP address or by using an alternate DNS server. In other words, multiple DNS servers need to be brought down to cause problems to the Internet.
Each top-level domain is managed by a particular company or group of companies. At https://www.iana.org/domains/root/db a list of top-level domains are listed and the main company/agency responsible for those domain names and DNS servers. If a top-level domain on this page is clicked, then the user is presented with information concerning the people responsible for the TLD and the DNS servers that manage the data. For instance, ".va" (http://www.iana.org/domains/root/db/va.html) is managed by six DNS servers. The page also provides the MAC address and IP address of the DNS server.
Root Name Servers are major DNS servers that redirect clients to the proper DNS server. Keep in mind that particular TLDs are managed by a specific DNS server. The Root Name Servers are on the Root Zone (beginning/top layer) of the Domain Name System (DNS). Root Name Servers are the first DNS servers that an Internet client queries for domain name resolution (convert a website name to an IP address). Obviously, these are very crucial servers. Each Root Name Server is designated a name "A" through "M". For instance, Verisign owns "A" and "J".
The thirteen Root Name Servers are not each a single computer/machine. Rather, a single Root Name Server may be a redundant collection of geographically separate machines. This provides extra security against cyber-attacks and natural disasters.
Most of the DNS servers use BIND (Berkeley Internet Name Domain). However, the Root Name Servers "H" and "L" use NSD (Name server Daemon) instead of BIND.
Understanding the structure of the DNS portion of the Internet is important for may security reasons. Also, it is good to see that the structure is indeed securely setup with redundant servers.