What is DNS? Guide to Managing DNS on Thai Hosting 2026
DNS (Domain Name System) is the internet's directory service, translating human-readable domain names like example.com into the IP addresses that computers use to communicate. Without DNS, you'd need to memorize IP addresses instead of domain names. Understanding DNS is essential for managing any hosting account effectively.
How DNS Works
- You type example.com in your browser.
- Browser checks its local DNS cache. If not found, queries your ISP's Recursive Resolver.
- Recursive Resolver queries Root Nameservers → TLD Nameservers (.com) → Authoritative Nameservers for example.com.
- Authoritative Nameservers return the IP address for example.com.
- Browser connects to the server at that IP address.
This entire process typically completes in milliseconds, despite involving multiple servers worldwide.
Essential DNS Record Types
A Record
Maps a domain or subdomain to an IPv4 address (e.g., example.com → 203.0.113.1). The most fundamental DNS record — every website must have one.
AAAA Record
Like an A record but for IPv6 addresses. Increasingly important as IPv4 addresses become scarce.
CNAME Record
Creates an alias pointing one domain/subdomain to another domain name (e.g., www.example.com → example.com, or blog.example.com → mysite.github.io). Useful for pointing to external services with potentially changing IPs.
MX Record
Specifies the mail servers responsible for accepting email for the domain. Uses priority numbers (lower = higher priority). Multiple MX records provide redundancy.
TXT Record
Stores arbitrary text data. Used for SPF (email spoofing prevention), DKIM (email signature), DMARC (email policy), Google Search Console site verification, and other service verifications.
NS Record
Specifies the authoritative nameservers for the domain. Changing NS records transfers DNS management to a different provider.
Managing DNS in DirectAdmin
- Login to DirectAdmin → Advanced Features → DNS Administration.
- Select the domain you want to modify.
- Add, edit, or delete DNS records directly in the interface.
- Click Save — changes take effect based on TTL propagation time.
DNS changes propagate globally in 15 minutes to 48 hours depending on the TTL value configured for each record.
DNS Records for Email
Correctly configured email requires several DNS records:
- MX Record: Points to your mail server (e.g., mail.example.com priority 10)
- A Record for mail: mail.example.com → mail server IP
- SPF (TXT): v=spf1 mx ~all (authorizes your MX servers to send mail)
- DKIM (TXT): Public key for cryptographic email signing
- DMARC (TXT): _dmarc.example.com — policy for handling SPF/DKIM failures
Frequently Asked Questions
How long does DNS propagation take?
Depends on the TTL (Time to Live) of the previous record. With TTL=3600 (1 hour), propagation takes up to 1 hour. NS record changes can take 24-48 hours. Reduce TTL to 300 before planned changes to speed up propagation.
What's the difference between a CNAME and an A record?
An A record directly maps a domain to an IP address. A CNAME maps a domain to another domain name, which then resolves to an IP. Use CNAMEs for external services (CDNs, SaaS tools) where the underlying IP may change.
Why can some people see my DNS changes but others can't?
DNS propagation is not instantaneous worldwide. Each resolver refreshes its cache based on its own TTL. It can take up to 48 hours for changes to be consistent globally — this is normal behavior, not an error.
How can I check current DNS records?
Use online tools like dnschecker.org, the dig command line tool, or dnsxray.com which has DNS lookup and propagation checking tools.