Your Friendly Guide to DNS Time To Live (TTL)

TL;DR: DNS Time To Live (TTL) is like an expiration date (in seconds) on your website’s address book entries (DNS records). It tells internet servers how long to “remember” (cache) things like your site’s IP address.

Introduction: What on Earth is Time To Live (TTL)?

TTL: Not Just for Secret Agents

You might have heard the term “Time To Live” or TTL thrown around while building your website or in hushed tones around the IT pod at work. It sounds a bit like something from a spy movie, but it’s actually a super important concept in how computers and networks handle information. Think of TTL as a built-in expiration date or a countdown timer for data. Its main job is to prevent old, stale information from clogging up the digital pipes indefinitely.

One place you see TTL is in the Internet Protocol (IP), the system that routes data packets across the internet. In IP packets, TTL acts like a “hop limit.” Every time a packet jumps from one router to the next, the TTL number goes down by one. If it hits zero before reaching its destination, the router knows something’s wrong (like the packet is stuck in a loop) and discards it. This keeps the internet running smoothly.

But We’re Talking DNS TTL Here!

Now, here’s where it gets a little tricky: the TTL we’re focusing on today, DNS TTL, is different. It shares the name, but it has nothing to do with those router hops or how long a data packet survives its journey.

Instead, DNS TTL is a specific instruction tucked inside a DNS record (think of DNS records as entries in the internet’s phonebook). This instruction tells other computers how long they’re allowed to “remember” or cache that specific piece of DNS information. This caching, controlled by TTL, is super important for making the internet fast, reliable, and manageable.

Building on What You Know

This guide assumes you’ve got the basics of DNS down, including concepts like DNS records (A, CNAME, MX, NS, etc.), authoritative nameservers, and recursive resolvers. (It’s designed to complement and build upon introductory materials, like the helpful guide “Don’t Fear the DNS: Your Definitive Guide to DNS Records – the Internet’s Phonebook.” Here, our focus shifts specifically to the intricacies of TTL within the DNS context, exploring its definition, purpose, impact, and best practices for effective management.

Why Should You Care About TTL? (Spoiler Alert!)

That little number called TTL? It’s more powerful than it looks. It’s the key to a balancing act: getting users the latest, freshest information versus making sure the internet’s address lookup system (DNS) runs quickly and efficiently. Your TTL settings directly control how fast changes you make (like updating your website’s address) spread across the internet. They also affect how much work your main DNS servers have to do and, ultimately, how fast your website loads for visitors. So yeah, understanding TTL isn’t just for tech wizards – it’s essential for anyone running anything online!

What is DNS TTL? Let’s Break It Down

The Official Definition (Made Simple)

In the world of DNS (the internet’s phonebook), Time To Live (TTL) is simply a number, measured in seconds, attached to every DNS record. This number tells DNS resolvers (like the ones your Internet Service Provider uses, or public ones like Google’s 8.8.8.8) and even your own computer or browser how long they are allowed to keep a copy of that DNS record in their memory (cache) before they need to throw it out or ask the official source (the authoritative nameserver) for a potentially newer version.²

Think of it like an “expiration date” or “best before” date stamped on a piece of information you got from the official source. When a resolver looks up the IP address for www.example.com, it gets the address and the TTL. It can then confidently give out that same IP address to anyone else who asks for www.example.com until that TTL timer runs out.

DNS TTL vs. IP Packet TTL: Don’t Mix Them Up!

This is super important: DNS TTL and IP Packet TTL are not the same thing, even though they share the name.

• IP Packet TTL: Is about the journey of a data packet. It’s a hop counter (usually starting around 64 or 128) that decreases with each router jump. Its job is to stop packets from looping forever.
• DNS TTL: Is about the freshness of DNS information. It’s a timer (in seconds) telling caches how long to trust a specific DNS record. Its job is to balance getting updates out quickly with keeping DNS lookups fast. Values can range from a few minutes (like 300 seconds) to a whole day (86400 seconds) or more.

Remember: DNS TTL = Cache Timer for DNS info. IP TTL = Hop Counter for data packets.

Who Sets TTL and How Is It Used?

The person managing a domain (the domain administrator) sets the TTL values on the authoritative DNS servers for that domain. Usually, you can set a specific TTL for each individual record (like your A record, MX record, etc.) in your domain’s settings (often called a zone file). If you don’t set one, there might be a default value applied, but it’s generally better to set them explicitly.

The value is always in seconds. So, a TTL of 3600 means “cache this for up to 3600 seconds,” which is one hour.

Here’s a key detail: TTL is the maximum time something can be cached. A resolver must discard or re-check the record after the TTL expires. However, it might decide to remove the record from its cache sooner if it needs to free up memory, for example. The main point of TTL is to ensure data isn’t treated as fresh for longer than the specified time.

There’s a small exception introduced relatively recently (RFC 8767): if a resolver absolutely cannot reach the authoritative server to get fresh data (maybe the server is down), it might be allowed to serve the old, expired (stale) data temporarily just to keep things working. This shows that while TTL is a strong rule, sometimes keeping services online takes priority.

The rules for DNS TTL are defined in technical documents called RFCs (Request for Comments) from the IETF (Internet Engineering Task Force). Key ones include RFC 1034/1035 (the originals), RFC 2181 (clarifications), RFC 2308 (negative caching), and RFC 8767 (using stale data). You don’t need to read them, but knowing they exist helps understand why TTL works the way it does.

Why DNS TTL is a Big Deal: The Core Jobs

DNS TTL isn’t just some obscure setting; it’s doing several really important jobs behind the scenes that affect how the internet works for you.

The Power Behind DNS Caching

TTL is what makes DNS caching possible, and caching is what makes the internet usable! Imagine if every single time you clicked a link or typed a web address, your computer had to ask the original source server for the IP address. The internet would grind to a halt!

Caching happens in layers:

1. Your ISP’s Resolver (or Public DNS): When you type www.example.com, your request usually goes to a big DNS server run by your ISP or a public service like Google (8.8.8.8) or Cloudflare (1.1.1.1). These are called recursive resolvers. When they look up a record, they get the TTL and store the answer in their cache. The next person using that same resolver who asks for www.example.com gets the answer instantly from the cache, as long as the TTL hasn’t expired.
2. Your Operating System (OS): Windows, macOS, and Linux also keep their own little DNS cache so they don’t have to bother the resolver every single time.
3. Your Web Browser: Chrome, Firefox, Safari, etc., usually have their own DNS cache, checking here first before even asking the OS. Browser caches often have shorter timers.
4. Applications: Some apps might do their own caching too.
5. Content Delivery Networks (CDNs): CDNs, which help websites load faster by storing content closer to users, rely heavily on TTL. They use it not just for their own DNS records but also for controlling how long browsers cache things like images and scripts.

How the Layers Work Together: The TTL set by the website owner (on the authoritative server) is the maximum time anyone is allowed to cache the record. But the actual time it stays cached for you depends on the shortest timer along the path. If your browser caches for 5 minutes, but the ISP resolver caches for 1 hour, your browser will still ask again after 5 minutes. If the authoritative TTL is 1 hour, but your browser only caches for 10 minutes, you’ll benefit from the browser cache for 10 minutes, then maybe the OS cache, then maybe the ISP cache, before a full lookup is needed again. It’s a chain, and the authoritative TTL sets the ultimate limit.

Controlling How Fast DNS Changes Spread (Propagation)

People often talk about DNS changes “propagating” like ripples in a pond. But it’s more like waiting for milk cartons to expire at different stores! DNS propagation is passive – it happens because caches expire, and TTL controls when that happens.

When you change a DNS record (like updating your website’s IP address), the change is instant on your authoritative server. But all the resolvers and browsers out there that already looked up the old record will keep using it until its TTL runs out. Only then will they ask again and get the new information.

So, TTL directly controls propagation speed:

• Low TTL (e.g., 5 minutes / 300 seconds): Caches expire quickly. Resolvers ask for updates sooner. Changes spread faster.²
• High TTL (e.g., 24 hours / 86400 seconds): Caches hold data for a long time. Changes take much longer to be seen everywhere.²

This is super important when you’re moving your website, changing email providers, or making other critical infrastructure updates. To check how your DNS is propagating, check out this handy DNS checker tool.

Keeping Your Authoritative DNS Servers Happy

Your TTL settings also affect how busy your own authoritative DNS servers get.

• High TTL: Good for your servers! Resolvers cache longer, so they ask your servers less often. This means less load, less bandwidth used, and potentially lower costs.
• Low TTL: Makes your servers work harder. Resolvers ask for updates frequently because caches expire quickly. This increases server load, uses more bandwidth, and might cost more if your DNS provider charges per query. You need to make sure your servers can handle it!

Making Websites Faster and More Reliable

How quickly and reliably DNS works directly impacts how users experience your website.

• Cache Hits = Speed: When a resolver can answer from its cache (a “cache hit”), it’s way faster than doing a full lookup. Since DNS lookup is often the very first thing that happens when loading a page, faster DNS means faster website loading. Happy users!
• Cache = Reliability: Good TTL settings help keep your authoritative servers stable by reducing their load. Plus, if your authoritative server has a temporary hiccup, resolvers with cached data can keep answering requests, potentially hiding the problem from some users.

But it’s a balance. While low TTLs mean more lookups (which can slightly increase average lookup time), they ensure users get the correct info faster after a change. High TTLs give fast lookups from cache but can be frustrating if users are sent to an old, broken address long after you’ve fixed it. Finding the right TTL is about balancing technical speed with user needs.

The TTL Balancing Act: High vs. Low – Finding the Sweet Spot

Choosing the right TTL is like Goldilocks finding the right porridge – not too hot (high), not too cold (low), but just right. Setting it wrong can cause headaches.

The Trouble with TTLs Set Too High

Using long TTLs (like 24 hours / 86400 seconds, or even more) is great for reducing load on your servers and making lookups from cache super fast. But beware the downsides:

• Changes Take Forever to Show Up: This is the biggest problem. If you update your website’s IP address or change where your email goes, it could take hours or even a full day for everyone on the internet to see the change. Resolvers will happily keep serving the old info until that long TTL finally expires.
• Users See Errors or Old Stuff: During that long wait, people might get sent to your old, possibly offline, server. This means error pages, connection failures, lost emails, or general confusion. Not a good look!
• Fixing Mistakes is Also Slow: If you make a mistake in a DNS change, rolling it back takes just as long. You’re stuck waiting for the high TTL to expire again for the correction to spread.

The Risks of TTLs Set Too Low

Setting TTLs super low (like 60 seconds, 30 seconds, or even less) makes changes spread lightning fast, which sounds great. But it comes with its own set of problems:

• Your Servers Get Hammered: This is the main drawback. Low TTLs mean resolvers constantly ask your authoritative servers for updates, massively increasing the number of queries. If your DNS hosting can’t handle the load, things can slow down or even break. It can also cost you more if you pay per query.
• Less Protection During Outages: Caching acts as a buffer if your authoritative server has a temporary problem. With low TTLs, that buffer disappears quickly. If your server goes offline, resolvers with expired caches can’t find your site, leading to outages for users who might otherwise have been fine. Longer TTLs offer more protection here.
• Maybe Slightly Slower on Average?: While lookups from cache are fast, low TTLs mean more cache misses. This forces more full lookups, which take longer, potentially increasing the average time it takes for some users to get a DNS answer.
• The “Rogue Resolver” Reality: Annoyingly, not all DNS resolvers out there actually respect super-low TTLs. Some big ISPs or public resolvers might enforce their own minimum cache time (like 60 seconds or 5 minutes) no matter what you set. They do this to protect themselves. So, setting a 5-second TTL might not actually give you 5-second updates everywhere.

Finding Your “Just Right”: What to Consider

So, how do you find the perfect TTL? It depends! Think about these things for each specific DNS record:

1. How Often Does It Change? If the record points to something stable (like a server with a fixed IP), you can use a higher TTL. If it changes often (like for dynamic services), you need a lower TTL.
2. How Fast Do Changes Need to Happen? For critical services needing quick failover or frequent updates, lower TTLs are essential. For less critical stuff, higher TTLs are fine.
3. Can Your DNS Servers Handle the Load (and Cost)? Be honest about your DNS hosting. Can it take the heat of frequent queries from low TTLs? Does your plan charge per query?
4. Is Slightly Old Info Okay for Users? For some things, seeing data that’s a few hours old is no big deal. For others (like finding the right server!), it needs to be fresh.
5. How Important is Riding Out DNS Glitches? If staying reachable even when your authoritative DNS has a brief problem is vital, longer TTLs help.

Thinking through these points will help you make smart TTL choices, balancing speed, cost, and reliability.

Setting TTLs for Different DNS Record Types

The “best” TTL often depends on what kind of DNS record you’re setting. Different records have different jobs and change at different rates. Let’s look at the common ones:

A / AAAA Records (Your Website’s Address)

• Job: These are the stars of the show! They link your domain name (like www.example.com) to the actual numerical IP address (IPv4 for A, IPv6 for AAAA) of the server hosting your site or service. Browsers need these to find where to go.
• TTL Tips:
  • Stable Servers (Most Websites): If your server’s IP address rarely, if ever, changes, you can use a higher TTL. Think 1 hour (3600s) up to maybe 24 hours (86400s). This is efficient. A common default used to be 4 hours (14400s), but 1 hour is popular now.
  • Dynamic Stuff (CDNs, Failover, Load Balancers): If the IP address might change often, or you need changes (like switching to a backup server) to happen fast, use a much lower TTL. Think 1 minute (60s) to 15 minutes (900s). Cloudflare, for example, uses 5 minutes (300s) for sites using its proxy service. AWS Route 53 often uses 60 seconds for services like load balancers.
• Watch Out: High TTL + changing IP = users can’t reach you. Low TTL + stable IP = unnecessary load on your DNS servers.

CNAME Records (Aliases or Nicknames)

• Job: A CNAME (Canonical Name) record acts like a nickname. It points one hostname to another “real” hostname. For example, www.example.com might be a CNAME pointing to example.com. The browser then looks up the A/AAAA record for example.com.
• TTL Tips:
  • Usually Static: The CNAME relationship itself (the nickname pointing to the real name) usually doesn’t change. So, a moderate to high TTL (1 hour to 24 hours) for the CNAME record itself is often fine. The caching of the final IP address depends on the TTL of the A/AAAA record that the CNAME eventually points to.
  • Changing the Target: If you need to change the CNAME to point to a different real name, you’d lower the CNAME’s TTL beforehand, just like with an A record migration.
• Watch Out: High TTL on a CNAME slows things down if you need to repoint the alias. Low TTL increases query load a bit. Resolvers cache the CNAME and the final A/AAAA record separately, each with its own TTL. If a CNAME points to another CNAME (a chain, generally not recommended ), the shortest TTL anywhere in that chain determines how quickly the final IP address cache expires.

MX Records (Where Your Email Goes)

• Job: Mail Exchange (MX) records tell the internet which servers handle incoming email for your domain. They also have a priority number (lower number = higher priority) to say which server to try first.
• TTL Tips:
  • Usually Stable: Your mail servers probably don’t change addresses often. A higher TTL (like 4 hours / 14400s to 24 hours / 86400s) is common and recommended for stability.
  • Mail Server Migration: This is critical! If you’re switching email providers or servers, lower the MX record TTL (e.g., 5 minutes / 300s to 1 hour / 3600s) well in advance of the switch.
• Watch Out & Email Delivery: If you migrate mail servers with a high TTL still active, sending servers will keep trying the old server based on their cache, leading to delayed or bounced emails. Setting MX TTL too low during normal times isn’t usually a big problem but slightly increases load. Correct MX records are vital for getting your email!

NS Records (Your Domain’s Authoritative Servers)

• Job: Name Server (NS) records delegate the authority for your domain’s DNS records to specific servers (your authoritative nameservers). They tell resolvers where to go to find the real answers (A, MX, TXT records, etc.) for your domain.
• TTL Tips:
  • Very Stable: These records almost never change unless you’re moving your entire DNS hosting to a new provider. Use a very high TTL (1 day / 86400s to 2 days / 172800s, or even longer). This is crucial for DNS stability and reduces load on the servers managing the top-level domains (like.com).
  • Nameserver Migration: You do need to lower the TTL when migrating, but it’s tricky. You need to lower the TTL for your NS records at your domain registrar (in the parent.com zone, for example) well in advance. Ideally, you also lower the TTL for the NS records in your own zone file on the old servers before the switch. This requires planning!
• Watch Out: Low TTLs on NS records are bad practice during normal operation – they hammer the TLD servers. High TTLs make nameserver migrations slow and require careful planning. The TTL set by the registrar (delegation) and the TTL set in your zone file both play a role in how fast migrations happen.⁵⁸

TXT Records (Text Notes for Verification, Email Security, etc.)

• Job: Text (TXT) records hold text strings used for various purposes, like proving you own a domain (for Google Search Console, etc.) or for email security settings (SPF, DKIM, DMARC).
• TTL Tips:
  • One-Time Verification: For records just used to prove ownership once, a high TTL (1 hour to 24 hours) is fine, as they won’t change.
  • Email Security (SPF/DKIM/DMARC): These don’t change often, but when they do (like adding a new email service to SPF), the change needs to spread reasonably quickly. A moderate TTL (30 minutes / 1800s to 4 hours / 14400s) is a good balance. Lower the TTL before making changes.
• Watch Out: Very high TTLs on email security records can delay policy updates, potentially causing email delivery issues if things change. Very low TTLs increase query load slightly.

SOA Record & Negative Caching (When Things Don’t Exist)

• Job: The Start of Authority (SOA) record is like the title page for your domain’s zone file. It has administrative info, including timers. One key timer (often called the “minimum” or “negative cache TTL” field) controls how long resolvers should remember when something doesn’t exist (an NXDOMAIN response).
• Negative Caching TTL: When someone looks up a non-existent subdomain (like idontexist.example.com), the authoritative server says “Nope, doesn’t exist.” The TTL for that negative answer is determined by the lower value between the SOA record’s own TTL and the SOA’s minimum/negative TTL field.
• TTL Tips:
  • Reasonably High Negative TTL (Recommended): Setting this to something like 15 minutes (900s) to 3 hours (10800s) is usually good. It stops resolvers from constantly asking about typos or non-existent records, saving load.
  • Low Negative TTL: Setting this very low makes resolvers ask again and again even for bad names, increasing server load.
• Watch Out: Setting the negative TTL too low hammers your servers with pointless queries. Setting it too high might slightly delay recognizing a newly created record if a resolver cached the “doesn’t exist” answer just before you added it.

SRV Records (Finding Specific Services)

• Job: Service (SRV) records help locate specific services (like chat servers or VoIP services) by providing the hostname and port number. They can also have priority/weight for load balancing.
• TTL Tips: Similar to A/AAAA records.
  • Stable Services: Moderate TTL (30 minutes / 1800s to 1 hour / 3600s) is often okay.
  • Dynamic/Failover: If service locations change or are used for failover, use a lower TTL (minutes).
• Watch Out: Same trade-offs as A/AAAA records regarding propagation speed vs. server load.

Table V.1: Quick Guide to Recommended TTLs (in Seconds)

Here’s a handy table summarizing typical TTL ranges. Remember, these are starting points – adjust based on your specific needs!

Record Type	Typical Use Case	Recommended TTL Range (Seconds)	Why?	Key Snippets
A / AAAA	Static Website/Server	3600 – 86400 (1h – 1d)	Balances efficiency & reasonable updates for stable IPs.	8
A / AAAA	Dynamic/Failover/CDN/LB	60 – 900 (1m – 15m)	Needs fast updates. Check provider limits (e.g., Cloudflare 300s 9).	8
CNAME	Standard Alias	3600 – 86400 (1h – 1d)	Alias itself is stable; target’s A/AAAA TTL matters for IP cache.48	8
MX	Standard Email Setup	3600 – 86400 (1h – 1d)	Stability preferred. Lower before migrating mail servers!	3
NS	Authoritative Nameservers	86400 – 172800+ (1d – 2d+)	Rarely changes. High TTL vital for DNS stability & less TLD load.	12
TXT	One-Time Domain Verification	3600 – 86400 (1h – 1d)	Set once, rarely (if ever) changes.	3
TXT	Email Security (SPF/DKIM etc)	1800 – 14400 (30m – 4h)	Balances update speed for policy changes & server load. Lower before.	8
SOA (Minimum/Negative)	Caching “Doesn’t Exist”	900 – 10800 (15m – 3h)	Reduces pointless queries for bad names. Max 3h suggested.24	2
SRV	Locating Services	1800 – 3600 (30m – 1h)	Depends on service stability, similar logic to A/MX.	43

Putting TTL into Practice: Smart Strategies

Knowing what TTL is and what values to use is great, but how do you actually manage it effectively? Here are some practical strategies.

Day-to-Day TTL: Keep it Steady

For your regular operations, match your TTLs to how often things actually change:

• Set and Forget Records: For things that almost never change (like your NS records, stable A/AAAA records, MX records for reliable email, verification TXT records), use longer TTLs (hours to days). This is efficient, saves load, and speeds up cached lookups.
• Records That Might Change: For things that could change more often (A/AAAA records for dynamic services, maybe email security TXT records if you change providers frequently), use shorter TTLs (minutes to an hour). This lets changes spread faster, but make sure your servers can handle the extra queries.
• Review and Document: Don’t just set TTLs and forget them forever. Check them periodically to make sure they still make sense for how you’re using your services. Writing down why you chose certain TTLs can also be helpful later.

The Migration Must-Do: Lower TTLs Before You Move!

This is probably the most important TTL trick to know. If you’re moving your website, changing email providers, or switching CDNs, you’ll be changing DNS records (like A, AAAA, CNAME, or MX).

• The Problem: If your TTL is high (say, 24 hours) when you flip the switch to the new server, many users will keep getting sent to the old server for up to 24 hours because of caching. Result? Downtime and unhappy users.
• The Fix: Lower the TTL for the record(s) you’re changing before the migration. A common temporary value is 5 minutes (300 seconds).
• Timing is Everything: You need to lower the TTL early enough. How early? At least as long as the old TTL value before your planned migration time. If your old TTL was 24 hours, lower it to 5 minutes at least 24 hours before you plan to make the switch. This gives caches time to expire the old high-TTL record and pick up the new low-TTL setting.
• Making the Move: When it’s time, make your server change (point website to new IP, activate new mail server) AND update the DNS record on your authoritative server simultaneously.
• Fast Updates: Now, because resolvers have the record cached with only a 5-minute TTL, they’ll quickly expire the old info and grab the new record shortly after you update it. Much less disruption!
• Clean Up After: Once everything is working smoothly on the new setup, change the TTL back to its normal, higher value (like 1 hour or 24 hours) to get back the benefits of caching.

TTL for High Availability, Failover, and Load Balancing

TTL is also key if you’re using DNS to help keep your site online even if a server fails (failover) or to spread traffic across multiple servers (load balancing).

• DNS Failover: This involves having a backup server ready. If your main server fails, a monitoring system automatically updates the DNS A/AAAA record to point to the backup. For this to work quickly, the record needs a very low TTL (often 60-300 seconds). This ensures resolvers quickly stop sending traffic to the failed server. Many DNS providers offering failover services enforce low TTLs automatically.
• DNS Load Balancing (Simple Round Robin): You can list multiple IP addresses (for different servers with the same content) in your A/AAAA records. Resolvers often cycle through them. High TTLs make this less effective, as users might stick to one server. Lower TTLs (minutes) help spread the load better but increase queries. More advanced DNS load balancing (like sending users to the closest server) also usually needs lower TTLs.
• The Trade-Off: Using low TTLs for failover/load balancing means more server load, potentially higher costs, and less protection if your DNS provider has issues. You have to decide what’s more important: near-instant failover or DNS efficiency/resilience.
• Cloud Provider Magic: Services like Cloudflare often manage TTLs automatically for their features (like their 300s default for proxied records). AWS Route 53 Alias records pointing to things like Load Balancers often bypass normal TTLs and use very short ones (like 60s) managed by AWS for quick scaling and failover.

Important Reality Check: DNS failover is not instant. Because of caching (including browsers and resolvers maybe ignoring super-low TTLs ), there will always be some delay. Some users will hit the failed server until their cache updates. DNS wasn’t built for real-time failover. For truly seamless failover, you often need other techniques like Anycast IPs or smart load balancers, sometimes used with DNS changes.

Table VI.1: TTL Strategy Cheat Sheet

Here’s a quick summary of TTL strategies for different situations:

Situation	Goal	Records Affected	TTL Strategy	Why?	Key Snippets
Routine (Stable)	Efficiency, Less Load	NS, MX, Stable A/AAAA/CNAME	High (Hours – Days)	Things rarely change; optimize caching.	8
Routine (Dynamic)	Balance Updates & Load	Changing A/AAAA/CNAME, SPF	Moderate (Minutes – Hours)	Allow reasonable update speed.	6
Planned Migration	Minimize Disruption	A/AAAA, MX, CNAME	Lower TTL (e.g., 5 min) before, make change, raise TTL after.	Ensure fast propagation during cutover.	2
DNS Failover / HA	Fast Recovery	A/AAAA	Low (e.g., 60-300 seconds)	Switch quickly to backup server on failure.	2
DNS Load Balancing	Spread Traffic	A/AAAA	Low to Moderate (Minutes)	Avoid clients sticking to one server too long.	34

Conclusion: Become a TTL Master for Healthy DNS!

So, there you have it! DNS Time To Live (TTL) isn’t so scary after all. It’s basically the expiration date for DNS records, controlling how long they can be cached. Its main job is to find that sweet spot between keeping DNS lookups fast (thanks to caching) and making sure everyone gets the latest information when things change.

Understanding TTL means understanding this trade-off: quick updates vs. efficient caching. There’s no single “perfect” TTL – the right value depends on the record type (A, MX, NS, etc.), how often the information changes, and what you need for your specific website or service (like planning a migration or setting up failover).

Smart TTL management is key to a healthy online presence. Use longer TTLs for stable records to save resources and speed up cached lookups. Use shorter TTLs when things change often or when you need updates (like migrations or failovers) to happen quickly. And definitely remember the trick of lowering TTLs before making major changes!

Paying attention to your TTLs isn’t a one-time task. Review them now and then to make sure they still make sense. By understanding and managing your TTLs wisely, you can help ensure your website or online service is fast, reliable, and ready for change. You’ve got this!