Question 1

What do DNS record types like A, CNAME, MX and TXT actually do?

Accepted Answer

Each record type answers a **different question** about a domain, which is why a single domain has many records and why editing the wrong one breaks something unrelated.

**A** — maps a name to an **IPv4 address**. The basic "where is this website" record.

**AAAA** — the same for **IPv6**. Pronounced "quad A".

**CNAME** — an **alias** pointing one name at another name, not at an address. `www.example.com` might be a CNAME to `example.com`, so changing the underlying address updates both.

**The rule people fall over:** a CNAME **cannot coexist with other records** at the same name. This is why you cannot normally put a CNAME on a bare domain (`example.com`) — it already has MX and NS records there. Providers work around it with non-standard **ALIAS** or **ANAME** records that behave like a CNAME but resolve server-side.

**MX** — where **email** for the domain should be delivered. Carries a **priority** number, and **lower is higher priority**, which is counterintuitive and routinely got backwards. Multiple MX records give failover.

**MX records are entirely independent of the website.** Changing hosting does not move email unless you change MX too — and accidentally replacing MX records when moving a site is the classic way to silently lose all incoming mail.

**TXT** — arbitrary text, now used mostly for verification and email authentication:

**SPF** — which servers may send mail for this domain.

**DKIM** — public key for verifying message signatures.

**DMARC** — what receivers should do when SPF or DKIM fail, and where to send reports.

**Domain ownership verification** for various services.

**NS** — which name servers are authoritative. These must match the delegation at your registrar.

**SRV** — service location with port and priority, used by VoIP and messaging protocols.

**CAA** — which certificate authorities may issue certificates for the domain, limiting misissuance.

**PTR** — reverse lookup from address to name, controlled by whoever owns the IP block rather than by you, and important for mail server reputation.

**SOA** — administrative parameters for the zone, including the negative caching TTL.

Question 2

What is the difference between a domain registrar, a DNS provider and a web host?

Accepted Answer

Three separate services that are frequently bought from one company and are entirely independent — and understanding the separation is what makes moving any of them possible without breaking the

Question 3

What does a DNS server actually do?

Accepted Answer

A DNS server translates names people can remember into the numeric addresses machines actually use to route traffic. Every connection you make begins with a lookup, and if that lookup fails nothing

Question 4

Who actually runs the internet?

Accepted Answer

Nobody, and several bodies with narrow remits — which is the accurate answer rather than an evasive one. There is no central authority; there are institutions that coordinate specific scarce

Question 5

What is an RFC, and how does an internet standard get made?

Accepted Answer

A Request for Comments is a numbered document published by the IETF describing a protocol, a procedure or an observation — and the name is a historical artefact that persists, because many RFCs are

Question 6

What is DNSSEC, and why isn't it everywhere?

Accepted Answer

DNSSEC adds cryptographic signatures to DNS records so a resolver can verify that an answer genuinely came from the domain's owner and was not altered in transit. It addresses a real weakness, and

Question 7

What are SPF, DKIM and DMARC?

Accepted Answer

Three DNS-published records that together let a receiving mail server answer one question: was this message really sent by the domain it claims to come from? Email was designed with no sender

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