Names and addresses solve different problems
People remember names more easily than numeric addresses. The Domain Name System stores records about names, including records that provide IP addresses. When you enter the example domain example.com, your device normally obtains the necessary information before trying to connect. DNS is not the website's content or a single switch that makes the internet work. It is one stage in a larger connection process.
Who answers a query?
A device or application may first reuse a cached answer. Otherwise it can ask a recursive resolver, which follows the domain hierarchy as needed to find an authoritative answer. Authoritative servers publish information for a DNS zone; recursive resolvers perform lookups on behalf of their clients. Caches reduce repeated work, so visiting a site does not necessarily trigger a fresh lookup through every part of the hierarchy.
Common record types
An A record provides an IPv4 address, while an AAAA record provides an IPv6 address. CNAME represents an alias to another domain name. MX identifies mail exchangers, TXT carries text used for purposes such as verification and mail policies, and NS identifies a zone's name servers. Multiple answers can be normal. A CNAME target is another name, not an arbitrary web-page URL or file path.
Why a change may take time
DNS records have a time to live, or TTL. Cached copies may remain usable for that period, so devices and resolvers querying at different times can return different answers. Editing a record does not instantly clear all caches. An accurate DNS answer also does not prove that a website is working: the destination service, routing, certificates and other connection steps still matter. Treat name resolution and application availability as related but separate checks.
Is the DNS server IP my public IP?
A DNS address identifies a resolver, not necessarily the exit seen by websites. It may be a local router, an ISP resolver or a public service; a browser can use separate encrypted DNS. See Long-running public DNS services: addresses and regional choices for service choices.
What does “DNS server not responding” mean?
It usually means no usable answer arrived within the expected time. The cause may involve the device, network path, resolver or authoritative DNS, rather than a failed server alone. NXDOMAIN is a reply saying the name does not exist, unlike receiving no response. Successful DNS still cannot guarantee a working connection, certificate or website. Cached answers may keep some sites working despite other lookup failures. See Will changing DNS make my internet or gaming faster? for performance effects.