TTL
Time To Live
ELI5 — The Vibe Check
TTL is how long DNS resolvers are allowed to remember (cache) your DNS records before checking again. A TTL of 3600 means 'remember this for 1 hour.' Set it low before making DNS changes so the update spreads fast. Set it high normally to reduce DNS lookups.
Real Talk
TTL is a field in DNS records that specifies the duration (in seconds) that a resolver should cache the record. Lower TTLs mean faster propagation of changes but more DNS queries. Higher TTLs improve performance by reducing DNS lookups.
Show Me The Code
# DNS records with TTL
example.com. 300 IN A 203.0.113.10 # 5 minutes
example.com. 86400 IN A 203.0.113.10 # 24 hours
# Pro tip: lower TTL before planned changes
# Change TTL to 300 one day before migrating servers
When You'll Hear This
"Lower the TTL to 5 minutes before switching servers." / "DNS is slow to propagate because the old TTL was 24 hours."
Related Terms
A Record
An A Record is the most basic DNS record — it just says 'this domain name = this IP address.' It's the phonebook entry itself.
CNAME (Canonical Name Record)
A CNAME is a DNS record that's like an alias or nickname. Instead of pointing to an IP address directly, it points to another domain name. So 'www.
DNS (Domain Name System)
DNS is the internet's phonebook. You type 'google.
MX Record (Mail Exchange Record)
An MX record tells the internet where to deliver emails for your domain. When someone sends an email to you@yoursite.