DNS Lookup — DNS Record Types Reference

Explore all DNS record types and learn how to perform DNS lookups on any operating system. A complete reference for understanding how the Domain Name System works.

What Is DNS?

The Domain Name System (DNS) is the internet's phonebook. It translates human-readable domain names like routerhax.com into machine-readable IP addresses like 93.184.216.34. Without DNS, you would need to memorize IP addresses for every website you visit.

When you type a URL into your browser, your device sends a DNS query to a resolver, which checks its cache or queries authoritative name servers to find the correct IP address. This process typically takes just a few milliseconds.

How DNS Resolution Works

1. Browser Cache: Your browser first checks its local DNS cache for a recent lookup of the domain.
2. OS Cache: If not found, the operating system checks its own DNS cache.
3. Recursive Resolver: The query goes to your ISP's DNS resolver (or a public resolver like 8.8.8.8).
4. Root Server: The resolver queries a root name server to find the TLD server (e.g., .com).
5. TLD Server: The TLD server points to the domain's authoritative name server.
6. Authoritative Server: Returns the final IP address for the domain.
7. Response: The IP address is cached at each level and returned to your browser.

How to Perform a DNS Lookup

Windows (nslookup)

Open Command Prompt and use the nslookup command:

nslookup routerhax.com
nslookup -type=MX routerhax.com
nslookup -type=TXT routerhax.com 8.8.8.8

macOS / Linux (dig)

Open Terminal and use the dig command:

dig routerhax.com
dig routerhax.com MX
dig routerhax.com TXT @8.8.8.8
dig +short routerhax.com A

Using host Command (Linux/macOS)

host routerhax.com
host -t MX routerhax.com

Popular Public DNS Servers

Provider	Primary DNS	Secondary DNS	Features
Google	8.8.8.8	8.8.4.4	Fast, reliable, global
Cloudflare	1.1.1.1	1.0.0.1	Privacy-focused, fastest
OpenDNS	208.67.222.222	208.67.220.220	Content filtering available
Quad9	9.9.9.9	149.112.112.112	Security-focused, blocks malware
Comodo	8.26.56.26	8.20.247.20	Security and filtering
AdGuard	94.140.14.14	94.140.15.15	Ad and tracker blocking

To change the DNS server on your router, follow our guide: How to Change DNS on Your Router.

DNS Security: DNSSEC

DNS Security Extensions (DNSSEC) adds cryptographic signatures to DNS records to prevent spoofing and cache poisoning attacks. DNSSEC uses DNSKEY and DS records to create a chain of trust from the root zone down to individual domains.

While DNSSEC does not encrypt DNS queries (that's what DNS-over-HTTPS and DNS-over-TLS do), it ensures the authenticity of DNS responses, preventing attackers from redirecting you to malicious websites.

Common DNS Issues and Troubleshooting

• DNS_PROBE_FINISHED_NXDOMAIN: The domain does not exist. Check for typos or try a different DNS server.
• Slow DNS resolution: Switch to a faster public DNS server like Cloudflare (1.1.1.1) or Google (8.8.8.8).
• DNS cache issues: Flush your DNS cache with ipconfig /flushdns (Windows) or sudo dscacheutil -flushcache (macOS).
• DNS propagation delay: After changing DNS records, it can take up to 48 hours for changes to propagate globally due to TTL caching.

Video Tutorial

Related Tools and Guides

• How to Change DNS on Your Router
• What Is DNS? - Complete beginner's guide
• What Is My IP Address?
• Subnet Calculator
• IANA Root Servers

Frequently Asked Questions

What is a DNS A record?

An A record maps a domain name to an IPv4 address. It is the most fundamental DNS record type. When you visit a website, your browser ultimately needs an A record to find the server's IP address. For example, routerhax.com might have an A record pointing to 93.184.216.34.

What is the difference between CNAME and A records?

An A record maps a domain directly to an IP address, while a CNAME record creates an alias pointing one domain to another domain. CNAME records are useful for subdomains like www.example.com pointing to example.com. You cannot use a CNAME at the root domain (zone apex).

How long does DNS propagation take?

DNS propagation typically takes 15 minutes to 48 hours, depending on the TTL (Time to Live) value set on the records. Lower TTL values mean faster propagation but more DNS queries. Before making important DNS changes, reduce the TTL in advance.

Should I use Google DNS or Cloudflare DNS?

Both are excellent choices. Cloudflare (1.1.1.1) is generally the fastest and focuses on privacy, promising not to sell user data. Google DNS (8.8.8.8) has a longer track record and wider global infrastructure. Either is a significant improvement over most ISP DNS servers.