What is DNS?
DNS is a Domain Name System. DNS is a system that translates human-readable domain names (like example.com) into IP addresses (like 123.456.789.123) that computers use to communicate with each other. It’s like the internet’s phonebook, mapping domain names to their corresponding IP addresses.
What types of Domain servers involved to load a webpage?
There are 4 types of servers involved in loading a web page.
1. DNS Recursor:
The client connects with the DNS recursion server to resolve the query. This server first checks the response of the Domain name in the cache. If there is no mapping in the cache, then this server calls the root server to know the IP address of the TLD server.
This server is responsible for resolving the domain name into an IP address.
2. Root Server:
The root server is a top-level server. There are 13 DNS root name server addresses known to every recursive resolver.
The root server responds to the IP of the TLD server according to the domain(.com, .net).
Root Server is handled by Internet Corporation for Assigned Names and Numbers(ICANN).
3. TLD Name Server:
TLD name server knows information related to specific domains.
Example: .COM server knows about information for all the domains ending with .COM.
After receiving a response from the root server, the recursive server connects with the TLD server to know the authoritative server IP address.
TLD server is handled by Internet Assigned Numbers Authority (IANA).
There are 2 groups of TLD servers:
i) Generic top-level domain: These are general domains. Example: .com, .org, .net
ii) Country specific top-level domains: These are country specific domains.
4. Authoritative Service- This is the last step for resolving the DNS query. Authoritative server returns the IP address of that domain name.
How Does DNS Work?
1. First user enters the website www.example.com in the browser.
2. Request is routed to DNS resolver. DNS resolver is managed by the user’s internet service provider(ISP).
3. DNS server first does a lookup into the cache, if found then returns IP address.
3. if cache miss, DNS resolver of the ISP forwarded this request to the DNS root name server.
4. DNS root name forwards this request to the authorised TLD name server. That TLD server returns the IP address of the authoritative server.
5. Authoritative server returns the IP of a domain to the domain resolver.
DNS Registration
Registry:
This is an organisation authorized by IANA that manages the registration of domain names within specific TLD.
Example:
.com handles by Verisign
.edu handle by Educause
Registrar:
Registrar is authorised by ICANN to manage the reservation and registration of Internet domain.
Example: GoDaddy
How Domain Registration Works:
1. A user wants to buy the domain name xyz.com and open the Registrar website.
2. The Registrar asks for user information and shows available domain names.
3. Registrar checks domain availability with Verisign(For .com) and registers the domain for the user.
4. Registrar responds to the user with domain details.
How to Access Domain Information?
We can access domain information using the below methods.
1. WHOIS : WHOIS is a text-based protocol used to query databases that store information about registered domain names, IP addresses, and other network resources. WHOIS queries can retrieve registration and ownership information for a given domain name or IP address. We can use whois from command line utilities or various online tools.
2. ICANN Lookup: ICANN is also returns domain information. We can do ICANN look from ICANN website only.
3. RDAP (Registration Data Access Protocol): RDAP is a newer protocol designed to replace WHOIS. It offers a more structured and standardized approach to accessing registration data for domain names, IP addresses, and autonomous system numbers (ASNs). RDAP provides better support for internationalization, authentication, and access control compared to WHOIS.