Technology & Computing
DNS TTL Propagation Window Calculator
Estimate the worst-case and average time for a DNS record change to propagate across caching resolvers based on TTL.
Your inputs
Change any value to update the result instantly.
Worst-case propagation time
3,600 seconds
Average propagation time
1,800 seconds
TTL in hours
1 hours
Resolvers affected during propagation window
1,000
Full propagation is never instant — resolvers only refresh a record once their cached copy's TTL expires.
Formula and working
Worst-case propagation = old TTL (last cached instant before change); Average propagation ≈ TTL ÷ 2 across resolvers with random cache ages
- 1
Collect the inputs
Record TTL = 3,600; Number of independent caching resolvers = 1,000
- 2
Apply the formula
Worst-case propagation = old TTL (last cached instant before change); Average propagation ≈ TTL ÷ 2 across resolvers with random cache ages
- 3
Result
Worst-case propagation time = 3,600 seconds
Frequently asked questions
Important limitation
This is an educational estimate based only on the values and formula shown. Verify current rates, rules, units, and professional standards before relying on the result. It is not personalized financial or investment advice.
Report a mistake or request an improvement
Tell us if a formula, unit, explanation, or result needs attention. Your message will include this calculator’s name and page.
Related calculators
TLS Handshake Latency Overhead Calculator
Estimate the extra round-trip latency added by TCP and TLS handshakes for TLS 1.2, TLS 1.3 1-RTT and TLS 1.3 0-RTT resumption.
AES-GCM Nonce Collision & Key Exhaustion Calculator
Estimate the safe number of messages encrypted under one AES-GCM key before random 96-bit nonce collisions become likely.
Binary, Octal, Decimal & Hexadecimal Multi-Base Converter
Convert a decimal number into binary, octal and hexadecimal representations and see its bit length.
ECC vs RSA Security Equivalence Calculator
Compare an elliptic curve key size to the RSA modulus length needed to achieve the same symmetric security strength.
Hash Collision Probability & Birthday Attack Calculator
Estimate the probability of a hash collision occurring among a set of hashed items, based on the birthday paradox.
IEEE 754 Floating Point Precision Calculator
Show the mantissa/exponent bit split, machine epsilon and representable range for IEEE 754 single or double precision.