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DNS (Domain Name System)

DNS, the Domain Name System, is the internet's directory: it translates human-readable domain names like example.com into the IP addresses that…

By Sofia Almeida · Senior Editor Updated 6 September 2026
In brief

DNS, the Domain Name System, is the internet's directory: it translates human-readable domain names like example.com into the IP addresses that machines use to route traffic. When a browser loads a site, it first asks a DNS resolver for the domain's records, gets back an address (and possibly other records — mail servers, verification strings, subdomain targets), and then connects.

Definition

DNS, the Domain Name System, is the internet's directory: it translates human-readable domain names like example.com into the IP addresses that machines use to route traffic. When a browser loads a site, it first asks a DNS resolver for the domain's records, gets back an address (and possibly other records — mail servers, verification strings, subdomain targets), and then connects.

The lookup is cached along the way for a duration set by each record's TTL (time to live).

DNS is foundational infrastructure, and because it sits before every connection, DNS problems present as "the whole site is down" even when the servers are fine. Common record types matter in day-to-day work: A and AAAA point a name at an IPv4/IPv6 address, CNAME aliases one name to another, MX directs email, TXT holds verification and policy records (domain verification, SPF, DKIM, DMARC), and NS delegates a zone to its authoritative servers.

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In context

For iGaming affiliates and operators, a few DNS realities recur. Migrations — moving hosts, putting a CDN in front, switching domains — are DNS changes, and the TTL determines how long the old value keeps being served after the change; lowering TTLs a day before a planned migration limits the cut-over window.

During the transition both old and new hosts must serve correctly, because different resolvers switch at different times.

DNS is also a security and deliverability surface. Correct TXT records (SPF, DKIM, DMARC) are what keep outreach and CRM email out of spam folders — a link-building campaign sending from a domain with broken SPF lands in spam and wastes the outreach.

Dangling DNS records — a CNAME still pointing at a decommissioned service — are a subdomain-takeover risk that can be exploited to host content under the brand's domain. And for sites behind a CDN or DDoS-protection layer, leaking the origin's real IP through an old A record or an unproxied subdomain undermines the protection.

Registrar and DNS-provider account security (with strong authentication) protects against domain hijacking, which for a revenue-generating site is close to a total-loss event.

Worked example

An affiliate migrates its main site to a new CDN. Because the A record's TTL was 24 hours and was not lowered beforehand, a portion of users and crawlers keep hitting the old host for a full day after the switch; some see errors during the window when the old host is already partly decommissioned.

On the next migration the team drops TTL to 300 seconds a day ahead and the cut-over is seamless.

Related terms

Frequently asked questions

How does DNS (Domain Name System) work in practice?+
For iGaming affiliates and operators, a few DNS realities recur. Migrations — moving hosts, putting a CDN in front, switching domains — are DNS changes, and the TTL determines how long the old value keeps being served after the change; lowering TTLs a day before a planned migration limits the cut-over window.
Can you give an example of DNS (Domain Name System)?+
An affiliate migrates its main site to a new CDN. Because the A record's TTL was 24 hours and was not lowered beforehand, a portion of users and crawlers keep hitting the old host for a full day after the switch; some see errors during the window when the old host is already partly decommissioned.
What terms are closely related to DNS (Domain Name System)?+
The closest related terms are CDN (Content Delivery Network), TLS/SSL certificate. Each is linked in the related-terms block below.
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