DNS
DNS is the piece of infrastructure every business depends on and nobody owns. It was configured once during a website project and has worked ever since, which is precisely why nobody can say how.
Most explanations either stop at "it turns names into numbers" or assume you are running a nameserver. Neither helps the person who needs to change a record and is not sure which company holds it.
This guide covers how resolution actually works, what each record type does, why propagation is not what you were told, and how to change things without breaking them.
In this guide you will learn:
Root, TLD, authoritative, and the caches in between.
A, CNAME, MX, TXT and the rest, and what each is actually for.
Nothing propagates. Caches expire. The difference matters.
Three companies, three jobs, and the confusion that costs hours.
Migrations, TTL planning, and the order of operations.
Response codes, lame delegations, and reading a dig output.
DNSSEC, cache poisoning, and what actually protects you.
What a record contained before somebody edited it.
Chapter 1
Root, TLD, authoritative, and the caches in between.
This chapter is not written yet. Drop the prose into
guide-bodies/<body>.html and rebuild.
Chapter 2
A, CNAME, MX, TXT and the rest, and what each is actually for.
This chapter is not written yet. Drop the prose into
guide-bodies/<body>.html and rebuild.
Chapter 3
Nothing propagates. Caches expire. The difference matters.
This chapter is not written yet. Drop the prose into
guide-bodies/<body>.html and rebuild.
Chapter 4
Three companies, three jobs, and the confusion that costs hours.
This chapter is not written yet. Drop the prose into
guide-bodies/<body>.html and rebuild.
Chapter 5
Migrations, TTL planning, and the order of operations.
This chapter is not written yet. Drop the prose into
guide-bodies/<body>.html and rebuild.
Chapter 6
Response codes, lame delegations, and reading a dig output.
This chapter is not written yet. Drop the prose into
guide-bodies/<body>.html and rebuild.
Chapter 7
DNSSEC, cache poisoning, and what actually protects you.
This chapter is not written yet. Drop the prose into
guide-bodies/<body>.html and rebuild.
Chapter 8
What a record contained before somebody edited it.
This chapter is not written yet. Drop the prose into
guide-bodies/<body>.html and rebuild.
Check yours
Everything in this guide, checked on your domain in about ten seconds. Free, no account, every finding shown in full.