DNS is one of those things that most people never think about until something breaks. Then it becomes the most important thing in the world for about two hours.
Here is what you actually need to know.
What DNS does
DNS translates human-readable domain names into IP addresses that computers can route to. When you type alejandroelbaz.com, DNS is the system that figures out which server should respond.
Think of it as a phone book for the internet. You look up a name, you get a number.
The records that matter
There are many DNS record types, but for most practical purposes you need to understand four:
A record — Points a domain to an IPv4 address. This is the most basic record. "When someone visits example.com, send them to this IP address."
CNAME record — Points a domain to another domain. Useful for subdomains. "When someone visits www.example.com, treat it like example.com."
MX record — Tells email servers where to deliver mail for your domain. Without correct MX records, your email does not work.
TXT record — Stores text data, commonly used for email authentication (SPF, DKIM, DMARC) and domain verification. These are invisible to visitors but critical for email deliverability and proving you own a domain.
Why changes take time
DNS changes are not instant because of caching. When a DNS resolver looks up your domain, it stores the answer for a period defined by the TTL (Time to Live) value. Until that cache expires, the old answer persists.
This is why DNS propagation can take minutes to hours. You are not waiting for a deployment — you are waiting for caches around the world to expire and refresh.
Practical advice
Lower your TTL before making changes. If your TTL is set to 86400 seconds (24 hours), change it to 300 seconds (5 minutes) a day before you plan to make DNS changes. This means caches will refresh quickly once you make the actual update.
Always verify changes with a tool like dig or an online DNS checker before assuming they have propagated.
And document every DNS change you make. Future you will thank present you.