DNS records of store.wikipedia.org.

• A and AAAA: the IPv4 and IPv6 addresses of the name. This is where a browser connects.
• CNAME: an alias. The name borrows every record of another name, so it can hold no other records of its own.
• MX: the servers that receive email for the domain. The lowest number is tried first.
• NS: the name servers that hold the domain's records. They answer every other question on this page.
• TXT: free text. Today it mostly carries mail rules (SPF) and proofs that you own the domain for Google, Microsoft and others.
• CAA: which certificate authorities may issue SSL certificates for the domain.
• SOA: the zone's own settings: its primary server, a contact address, a serial number and the timers other servers follow.

The TTL is how long any resolver may keep an answer before asking again. When you change a record, people whose resolver already holds the old answer keep seeing it until that time runs out. That waiting is what people call propagation: nothing travels, old copies simply expire.

Planning a move? Lower the TTL to five minutes a day before, make the change, then raise it again once everything works.

This page asks Cloudflare's public resolver (1.1.1.1) over an encrypted connection. Your internet provider's resolver may still hold an older answer until its TTL runs out, and records that exist only inside a company network never show up on the public internet.

• No A record on the bare domain: the site works at www. but not without it.
• A CNAME on the bare domain: the standards forbid it, because that name must also hold NS and SOA records. DNS hosts offer "flattening" or ALIAS records instead.
• An MX pointing to an IP address or to an alias: an MX must name a host with its own A or AAAA record.
• SERVFAIL: the domain's name servers are down, misconfigured, or a DNSSEC signature does not check out.