What Is TTL in DNS? Check Any Domain's TTL
Look up a domain to see the TTL of each record in seconds and in words, and what it means for caching and changes.
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How to use the DNS TTL lookup tool
- Type the domain name into the input at the top of the tool. Enter the bare domain, such as example.com.
- Choose a resolver from the resolver list: Cloudflare or Google.
- Press Look up. Until you press it, the page shows the recorded example for example.com.
- Read the summary rows: Records found, Lowest TTL, Highest TTL, SOA minimum (negative caching limit) and Status.
- Scan the records table. Each row gives the record’s TTL in seconds, the TTL in words and the value. If an A answer includes a CNAME, that CNAME is listed first.
- Check for a warning. The tool shows one when a set of records with the same name and type has different TTLs.
- Copy the
digornslookupcommand shown for the same query if you want to repeat the lookup in a terminal.
The lookup starts only when you press the button, and it asks for six record types at once. Each lookup is sent to the resolver you selected, so run it again with the other resolver if you want to compare answers. The TTLs you see are the values the resolver currently holds, which may be lower than the values in the zone. The explanation below covers why.
What is TTL in DNS
TTL, or time to live, is a number of seconds stored with each DNS record that tells caching resolvers how long they may keep the record. When the time runs out, the resolver must ask the authoritative name server again. A TTL of 0 means the answer is used only for the request in progress and is not cached.
A TTL is an unsigned 32-bit number, so the largest value it can hold is 2147483647 seconds, about 68 years. Values such as 300 (5 minutes), 3600 (1 hour) and 86400 (1 day) are common in practice. The number is set in the zone file by the domain owner, and resolvers pass it on to their users.
Caching resolvers count the TTL down. The figure you see in a lookup is the time left in the resolver’s cache, not the value set in the zone. In the recorded example for example.com, the A record shows 139 s and the SOA shows 11 s. Ask again a few seconds later and the numbers fall until the cache refreshes. To read the value set in the zone, ask one of the domain’s own name servers. Find them with an NS lookup, then run a command such as dig @ns-name example.com A.
All records with the same name and type form a set, called an RRset. Those records should share one TTL. If they differ, a resolver acts as if every record has the lowest TTL in the set.
What TTL should I use before changing DNS
Lower the TTL at least one old TTL before you make the change. Once the old TTL has passed, every resolver that cached the record will have fetched the lower value. Then make the change, and raise the TTL again after the new value has settled.
Without this step, resolvers that cached the old record keep serving it until its TTL runs out. The old value can therefore stay visible for up to the old TTL.
Shorter TTLs mean more queries reach your name servers. Longer TTLs mean fewer queries but slower changes. The tool shows the TTLs you have today, and it does not suggest a value.
Worked examples
| Input | Result |
|---|---|
| example.com | 10 records, lowest TTL 11 s (11 seconds), SOA record |
| github.com | 35 records, lowest TTL 52 s (52 seconds), A record |
| google.com | 12 records, lowest TTL 36 s (36 seconds), SOA record |
Calculated by the tool above; open it with the same values to see each step.
Frequently asked questions
What is a good TTL for DNS records?
There is no single correct value. The tool does not recommend a number. Short TTLs such as 300 seconds allow quicker changes but send more queries to your name servers. Longer values such as 3600 or 86400 seconds reduce that load but slow down changes.
Why is the TTL shown lower than the one I set?
The resolver is counting down the time the record has spent in its cache. Ask the domain’s own name servers to see the value set in the zone. Repeat the lookup later and the number will be lower again until the cache refreshes.
Does a TTL of 0 mean no caching?
Yes. A TTL of 0 means the record is used only for the request in progress and is not stored. Every new query goes back to the authoritative name server.
How long does DNS propagation take?
There is no fixed time. After a change, the old value can persist for up to the old TTL, because resolvers keep their cached copies until then. Lowering the TTL before the change shortens that window.
What does the SOA minimum mean?
The SOA minimum is the negative caching limit. Negative answers, such as a name that does not exist, are cached for the smaller of the SOA record’s TTL and the SOA minimum field. The tool shows this value in the summary rows.
Related tools
- DNS Record Lookup tools: Use this to look up several record types for a domain in one place.
- NS Lookup: Use this to find a domain’s name servers before you read zone values directly from them.
- DNS Propagation Checker: Use this to see whether a change has reached resolvers after you update a record.
- DNS Record Types: Use this to learn what each record type, such as A, MX or TXT, is for.
- A Record Lookup: Use this when you only need the IPv4 address and TTL of a domain.