What is TTL in DNS?

Picture this. You just switched hosting providers and updated your A record to point to the new server. You refresh your site and nothing has changed. The old site is still loading. You check your DNS panel and the new record is saved. So what is going on?

The answer is TTL. When you set a DNS record, you also set a TTL value that tells every DNS server on the internet how long they can keep a cached copy of that record. Until that timer runs out, those servers will keep serving the old information, even after you have made a change. Understanding how DNS works starts with understanding TTL, because it controls the speed of every DNS change you make.

What does TTL stand for?

TTL stands for time to live. In the context of DNS, it is a number attached to every DNS record that tells servers how many seconds they are allowed to cache that record before they need to go back and check for a fresh copy.

Every DNS record you create has a TTL value. Your DNS record types all use it. A records, CNAME records, MX records, TXT records. Each one has its own TTL setting, and each one can be set to a different value depending on how often you expect that record to change.

How does TTL work in plain terms?

When someone types your domain into a browser, their device asks a DNS server for your website's IP address. That DNS server looks up your A record and gets the answer. But it also reads the TTL value attached to that record.

If your TTL is set to 3600, the DNS server stores that answer for 3,600 seconds (one hour). For the next hour, anyone who asks that same DNS server for your domain gets the cached answer. The server does not check again until the timer expires.

Once the TTL runs out, the next request triggers a fresh lookup. The DNS server goes back to the source, grabs the current record, reads the new TTL value, and starts the countdown again.

Think of it like a sticky note on a fridge. Someone writes down the phone number for the pizza place and sticks it to the fridge. Everyone in the house uses that number until the note expires (gets thrown away). Then someone has to look up the number again. If the pizza place changed its number in the meantime, the new number only gets picked up after the old note is gone.

How is TTL measured?

TTL is always measured in seconds. Here are the most common values and what they translate to in real time.

• 300 equals 5 minutes
• 600 equals 10 minutes
• 1800 equals 30 minutes
• 3600 equals 1 hour
• 14400 equals 4 hours
• 43200 equals 12 hours
• 86400 equals 24 hours

Most DNS panels show the TTL field when you create or edit a record. Some use a dropdown with preset options like "1 hour" or "automatic." Others let you type the exact number of seconds.

What happens when TTL is high?

A high TTL means DNS servers cache your record for a long time. If your TTL is 86400 (24 hours), every DNS server that looks up your record will hold onto that answer for a full day before checking again.

The benefit is fewer DNS lookups. When thousands of visitors load your site, their DNS resolvers already have the answer cached. That means slightly faster page loads and less strain on DNS infrastructure.

The downside is that changes take longer to spread. If you update your A record with a 24-hour TTL, some visitors might still see the old site for up to 24 hours. You are trading speed of changes for efficiency of lookups.

What happens when TTL is low?

A low TTL means DNS servers refresh your record more often. If your TTL is 300 (five minutes), servers throw away the cached answer every five minutes and look it up again.

The benefit is that changes spread fast. If you update a record with a five-minute TTL, most of the internet sees the new value within minutes.

The downside is more DNS queries. Every time the cache expires, the server has to do a fresh lookup. For a high-traffic site, that means more load on your authoritative DNS servers. For most small to medium brands, the difference is not noticeable. But keeping a permanently low TTL when you are not making changes is unnecessary.

What is a good default TTL?

For most DNS records, 3600 (one hour) is a solid default. It strikes a balance between two things.

• Changes propagate within an hour, which is fast enough for routine updates
• DNS servers do not have to look up your record every few minutes when nothing has changed

If your DNS records rarely change (and for most brands they do not), you can safely use 3600 or even 14400 (four hours). The only time you need a lower TTL is when you know a change is coming.

When should you lower your TTL?

Lower your TTL before making any major DNS change. Here are the situations where a low TTL saves you time and headaches.

• Switching hosting providers and updating your A record
• Migrating your website to a new platform
• Changing your email provider and updating MX records
• Pointing a domain to a website for the first time
• Setting up a failover or load balancing system

In each of these cases, you want the change to take effect as quickly as possible. A low TTL makes that happen.

How to lower TTL before a migration

There is a simple strategy that experienced DNS administrators use before any server migration. It works in three steps.

1. 24 to 48 hours before the change, lower your TTL to 300 (five minutes). This gives the old high TTL time to expire across all DNS servers worldwide. By the time you are ready to make the actual change, most servers will be checking every five minutes
2. Make the DNS change. Update the A record (or whichever record you are changing) to the new value. Because the TTL is already low, DNS servers around the world pick up the new value within minutes
3. After the change is confirmed and working, raise the TTL back to 3600 or your preferred default. This stops the constant lookups now that the change is done and the new record is stable

Skipping step one is the most common mistake people make. If your TTL is still set to 86400 when you make the change, some DNS servers will serve the old record for up to 24 hours because their cache has not expired yet. Lowering the TTL in advance prevents that.

How do TTL and DNS propagation connect?

DNS propagation is the process of your updated DNS records spreading across all the DNS servers around the world. TTL is the main factor that controls how long that process takes.

When people say "DNS propagation can take up to 48 hours," what that means is that some DNS servers might have cached your old record with a high TTL, and those servers will not check for updates until their timer runs out.

A low TTL before a change means faster propagation. A high TTL means slower propagation. It is that direct. The 48-hour number is a worst-case scenario for records with a 24-hour TTL, because some servers may have cached the record right before you made the change and still have nearly a full day left on their timer.

Common TTL mistakes

Two mistakes come up more than any others when it comes to TTL.

Forgetting to lower TTL before a change. This is the big one. You update your A record to point to a new server, but your TTL was set to 86400. Now some visitors see the new site and some see the old one, and you have no choice but to wait it out. Always lower TTL 24 to 48 hours before making DNS changes.

Setting TTL too low permanently. A TTL of 60 seconds means every DNS server checks for updates every minute. If your records are not changing, this just creates unnecessary DNS traffic. It can also make your site slightly slower for first-time visitors whose DNS resolver has to do a fresh lookup more often. Use a low TTL temporarily when changes are planned, then raise it back.

How WEMASY handles TTL

When you connect a custom domain to your WEMASY website, the platform handles DNS configuration as part of the setup process. WEMASY sets sensible TTL defaults for the records you need, so you do not have to guess which values to use.

If you are migrating to WEMASY from another provider, the domain setup guide walks you through lowering your TTL before making the switch, so the transition happens smoothly. WEMASY includes hosting, SSL, and domain management under one subscription. See what is included in each plan on the WEMASY pricing page.

What comes next

Now that you understand what TTL is and how it controls the speed of DNS changes, the next chapter covers how DNS propagation works. You will learn what happens behind the scenes when a DNS record updates, why propagation is not instant, and how to check whether your changes have spread. For the full picture of how the domain name system operates, revisit the chapter on how DNS works.

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