Why do DNS changes take 'up to 48 hours'?

Caching. Resolvers keep answers for the record's TTL, so old values persist until caches expire; the quoted 48 hours is a worst-case umbrella. Lowering the TTL ahead of a planned change shrinks the window to minutes — the standard migration trick.

Should my DNS live at the registrar, the host, or a DNS provider?

Anywhere reliable — what matters is knowing which one currently answers (the NS records) and keeping access to it. Consolidating at a competent provider simplifies life; the real hazard is split administration where nobody is sure which panel is live.

What is DNS? — Getting Digital glossary

DNS (Domain Name System)

Also: domain name system, nameservers, DNS records

DNS is the internet's address book: the distributed system that translates human-readable domain names into the machine addresses and service pointers that actually route traffic — and the control panel where a domain's fate is decided.

The lookup behind every click

Before any page loads, a resolver asks the DNS hierarchy where the domain name points: root servers refer to the top-level-domain servers, which refer to the domain's authoritative nameservers, which answer from its zone — the collection of records its owner controls. Answers are cached along the way for the record's TTL (time to live), which is why the system survives its own scale, and why changes take time to be seen everywhere.

A / AAAA — name to IPv4 / IPv6 address: the record that puts a site on a server.
CNAME — name to another name: how subdomains follow a platform's changing addresses.
MX — where the domain's email is delivered; unrelated to where the website lives.
TXT — free-form proofs: domain verification, SPF/DKIM email authentication policies.
NS — which nameservers speak for the domain: the delegation itself.

Operationally, DNS is where hosting decisions become real: pointing A records at a new server IS the migration, and the NS records decide who administers all of it — the registrar, the host, or a dedicated DNS provider. The classic pitfall is forgetting that mail and web are independent: moving a website while leaving MX records untouched is routine; nuking them in the same edit is a support ticket cliché.

Key takeaways

→DNS resolves names through a cached hierarchy ending at your zone's records — A/AAAA for the site, MX for mail, TXT for proofs, NS for who's in charge.
→Migrations happen in DNS: repointing records moves the site, TTLs decide how fast the world notices, and web and mail move independently.

Related concepts

RelatedDomain Name
The domain is the rented name; DNS is the system that makes it point somewhere.

FAQ

Why do DNS changes take 'up to 48 hours'?: Caching. Resolvers keep answers for the record's TTL, so old values persist until caches expire; the quoted 48 hours is a worst-case umbrella. Lowering the TTL ahead of a planned change shrinks the window to minutes — the standard migration trick.
Should my DNS live at the registrar, the host, or a DNS provider?: Anywhere reliable — what matters is knowing which one currently answers (the NS records) and keeping access to it. Consolidating at a competent provider simplifies life; the real hazard is split administration where nobody is sure which panel is live.