The DNS server converts domain names to IP addresses and vice versa. Every computer connected to the internet is connected to a DNS server. DNS servers are managed by ICANN. When connecting through an ISP, the connection is established with their DNS server. There are 13 root servers worldwide that contain a list of authoritative DNS servers for top-level domains like .com. Authoritative name servers provide actual answers to DNS queries. DNS records map domains to IP addresses and include records like A, NS, MX, CNAME and SOA.

1. DNS Server
(DOMAIN NAME SYSTEM)

2. What is DNS?
● Domain Name System (DNS) converts the domain name of a Web site
to it's IP address and vice versa.
● Every computer that is connected to the internet is also connected to a
DNS server.
● The connection of domain names to IP addresses is managed and
regulated by ICANN ( Internet Corporation for Assigned Names and
Numbers).

3. www.clado.com
IP
ofw
w
w
.clado.com
ISP1. Cache
2. /etc/hosts
3. /etc/resolve.conf(nameserver)
Root Server
IP of TLD (.com)
TLD server
IP of Authority
Name
server(clado.c
om)
Authority
Name
server
IP of www.clado.com
IP of www.clado.com
IP
of www.clado.com
Web Server
DNS cache server

4. What is Internet Service provider(ISP)?
● When you setup a connection through your Internet Service
provider, you are actually establishing a connection with their
DNS server.

5. What is a DNS Root Server?
● The contents of the root zone file is a list of names and numeric
IP addresses of the authoritative DNS servers for all top-level
domains (TLDs) such as com, org, edu, or the country code
top-level domains.
● There are only 13 root servers in the entire world

6. What is Authority Name server?
● An authoritative name server provides actual answer to your DNS
queries .

7. Types of DNS Servers
1. Primary DNS Servers (Master).
2. Secondary DNS Servers (slave).

8. DNS Records
● DNS records are basically mapping files that tell the DNS server
which IP address each domain is associated with, and how to handle
requests sent to each domain.
● Main DNS Records are:
A, AAAA, CNAME, MX, PTR, NS, SOA, SRV, TXT, and NAPTR.

9. DNS Records
● SOA - record stands for “State of Authority” and is easily one of the
most essential DSN records because it stores important information
like when the domain was last updated and much more.
● NS -record stands for “name server” and indicates which Name
Server is authoritative for the domain.
clado.com. IN NS ns1.clado.com.

10. DNS Records
● A - which stands for “address” - indicating the actual IP address of
the domain.
clado.com. IN A 139.59.29.237
● AAAA - record is an IPV6 address record that maps a hostname to a
128-bit Ipv6 address. Regular DNS addresses are mapped for 32-bit
IPv4 addresses.

11. DNS Records
● CNAME - record stands for “canonical name” - make one domain an
alias of another domain.
clado.com. IN A 139.59.29.237
main.clado.com. IN CNAME clado.com.
● MX - record stands for “mail exchange” - a list of mail exchange
servers that are to be used for the domain.
Mail.clado.com. IN A 139.59.29.237
clado.com. IN MX mail.clado.com.
● PTR -record stands for “pointer record” and maps an Ipv4 address to
the CNAME on the host.