TTL (Time To Live)

What is DNS?

Domain Name System = Phone book of the internet Converts google.com to 142.250.194.46

TTL = How long to remember/cache a DNS answer

When DNS Resolver gets an answer, it caches (remembers) it for a certain time. TTL tells it "how long to remember this answer before asking again."

Simple Example:

DNS Record:

google.com → 142.250.194.46
TTL: 300 seconds (5 minutes)

What happens:

First time:

• You ask: "Where is google.com?"
• DNS Resolver asks Route 53
• Route 53: "142.250.194.46, remember this for 300 seconds"
• DNS Resolver caches it

Within 5 minutes (TTL not expired):

• You ask again: "Where is google.com?"
• DNS Resolver: "I remember! It's 142.250.194.46" (doesn't ask Route 53)
• Faster response!

After 5 minutes (TTL expired):

• You ask: "Where is google.com?"
• DNS Resolver: "My memory expired, let me ask again"
• Asks Route 53 for fresh answer