DNS & Networking Basics

What is DNS?

The Domain Name System (DNS) translates human-readable domain names (like example.com) into IP addresses that computers use to communicate. It's often called the "phone book of the internet."

Common DNS Record Types

• A: Maps a domain to an IPv4 address
• AAAA: Maps a domain to an IPv6 address
• CNAME: Alias pointing to another domain name
• MX: Mail server for the domain (with priority)
• TXT: Arbitrary text, used for SPF, DKIM, domain verification
• NS: Nameserver responsible for the domain
• SRV: Service location (host, port, priority, weight)

IP Addresses & CIDR

IPv4 addresses are 32-bit numbers written as four octets (e.g., 192.168.1.1). CIDR notation (192.168.1.0/24) defines a range of IPs by specifying how many bits are fixed (the network prefix).

192.168.1.0/24
  Network:   192.168.1.0
  Broadcast: 192.168.1.255
  Usable:    192.168.1.1 – 192.168.1.254
  Hosts:     254

10.0.0.0/8     → 16,777,214 hosts (Class A)
172.16.0.0/12  → 1,048,574 hosts (Class B private)
192.168.0.0/16 → 65,534 hosts (Class C private)

IPv4 vs IPv6

• IPv4: 32-bit, ~4.3 billion addresses, e.g. 93.184.216.34
• IPv6: 128-bit, virtually unlimited, e.g. 2606:2800:220:1:248:1893:25c8:1946

Common Mistakes

• CNAME at zone apex: most DNS providers don't allow CNAME on the root domain. Use ALIAS or A records instead.
• Low TTL on stable records: use higher TTLs (3600+) for records that rarely change to reduce lookup latency.
• Forgetting reverse DNS: email deliverability often requires PTR records matching your sending IP.

Use our DNS Record Formatter, IP Validator, and CIDR Calculator to work with networking data.