What Is DNS and Why Does It Matter for Your Website?
DNS explained in plain language: what it does, the records you need and how mistakes cause downtime.
DNS, the Domain Name System, is the internet’s address book. When someone types your domain, DNS tells their browser which server to contact. When someone emails you, DNS tells their mail server where to deliver the message.
The records you should know
- A and AAAA: point a name to an IPv4 or IPv6 address.
- CNAME: makes one name an alias of another, such as www pointing to your main domain.
- MX: tells the world which servers receive your email.
- TXT: holds text such as SPF, DKIM and domain verification codes.
- CAA: limits which certificate authorities may issue certificates for your domain.
Why it matters
DNS sits in front of everything. If it is slow, the first step of every page load is slow. If it is wrong, your site or email disappears. If it is hijacked, visitors can be sent to the wrong place.
Common mistakes
- Leaving an old A record pointing at a previous server, so some visitors reach the wrong one
- Forgetting that a domain has both IPv4 and IPv6 records
- Changing name servers before copying all records
- Missing SPF or DKIM, which sends email to spam
Changing DNS safely
Lower the TTL (the cache time) a day before a move, copy every record to the new provider, make the change, then check from several networks. Keep the old setup running until you are sure everything works.
Frequently asked questions
How long does a DNS change take?
Anywhere from minutes to a day or more, depending on the old record’s cache time (TTL) and on resolvers that cache longer.
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