DNS propagation explained: Why domain changes are not immediately visible
When you change nameservers, A records, MX records, or other DNS data, the change is not always immediately visible everywhere. This is due to DNS caches, TTL values, and the global distribution of DNS information.
Many customers expect a DNS change to work immediately. In practice, however, it can happen that a domain already points to the new website for you, while it still loads the old server for another visitor. This behavior is normal and is often referred to as DNS propagation.
DNS stands for Domain Name System. It translates domain names like yourdomain.ch into technical destination information, for example, an IP address. For the internet to work quickly, DNS responses are cached in many places. It is precisely this caching that causes changes not to be immediately visible worldwide.
DNS propagation is not a hosting error. It is a normal technical process. During this time, visitors may see different results depending on their location, internet service provider, and cache.
What happens during a DNS change?
If you change the A record of your domain, for example, you are telling the DNS system: "This domain should point to a different IP address in the future." This change is stored in the authoritative DNS zone. This is the DNS zone officially responsible for your domain.
However, browsers and devices do not query the authoritative DNS zone directly every time they are accessed. Instead, they often use cached DNS responses. These caches can be located at:
- Your browser,
- Your operating system,
- Your router,
- Your internet service provider,
- Public DNS resolvers such as Google DNS, Cloudflare DNS, or Quad9,
- Other DNS servers along the way.
As long as a cache still has an old response saved, the domain may continue to point to the old destination. Only when the cache expires or is updated does the new DNS information appear.
What does TTL mean?
TTL stands for Time To Live. This value indicates how long a DNS record may be cached. The TTL is specified in seconds. A value of 3600 means one hour, for example, and a value of 14400 means four hours.
If a DNS record has a high TTL, it can take longer for a change to become visible everywhere. A lower TTL can be helpful for planned migrations because DNS resolvers query the entries again more quickly. However, the TTL should not be set unnecessarily low, as this generates more DNS queries.
If a domain migration is planned, it may be useful to lower the TTL a few hours or a day before the actual change. After a successful migration, the TTL can be set back to a normal value.
Which DNS changes are affected?
DNS propagation generally affects all DNS records. Customers notice delays particularly frequently with the following changes:
- Nameserver changes: The entire DNS zone will be managed by other nameservers in the future.
- A record: The website points to a new IPv4 address.
- AAAA record: The website points to a new IPv6 address.
- CNAME: A subdomain points to a different hostname.
- MX records: Emails will be received by different mail servers in the future.
- TXT records: Entries for SPF, DKIM, DMARC, or domain verification are changed.
Why do different people see different results?
DNS is distributed worldwide. A visitor in Switzerland may already see the new website, while a visitor in Germany, Italy, or France still reaches the old server. Even two people in the same country may see different results if they use different internet providers or DNS resolvers.
Additionally, the local cache plays a role. Your computer or browser may have old DNS data saved, while a smartphone using mobile data already uses the new address. Therefore, testing across different networks is often helpful.
How long does DNS propagation take?
Many DNS changes become visible within a few minutes to hours. With nameserver changes or unfavorable cache situations, it can take longer. There is no blanket guarantee, as different places on the internet cache for different lengths of time.
Typical empirical values:
- A, AAAA, CNAME, or TXT changes: often visible within a few minutes to a few hours.
- MX changes: often visible within a few hours, depending on TTL and mail server caches.
- Nameserver changes: can take longer because the domain delegation is affected.
Important for domain migrations
During DNS propagation, old hosting or mail services should not be deleted too early. Otherwise, visitors or emails may still end up at the old destination, even though it has already been removed.
How can I check if DNS has already been updated?
You can check DNS changes in several ways:
- Open the domain in a private browser window,
- Test from a different network, for example, mobile data instead of Wi-Fi,
- Clear your browser cache,
- Restart your router or computer if local caches are suspected,
- Use DNS checking tools to compare different locations,
- Check DNS records directly via terminal commands like
digornslookup.
Example using dig:
dig yourdomain.ch AFor an MX record, you can check, for example:
dig yourdomain.ch MXCommon misconceptions about DNS propagation
1. "It works for me, so it must work everywhere"
This is not necessarily true. Your own resolver may already be updated, while other resolvers are still providing old data.
2. "The domain isn't working, so the hosting is broken"
Not necessarily. If DNS still points to the old server, the request does not reach the new hosting at all. In this case, the problem is not with the website, but with the DNS destination or cache.
3. "I'll just change the DNS records several times in a row"
Multiple changes during propagation can make troubleshooting more difficult. It is better to set the entries cleanly, document them, and check the update specifically.
4. "Nameservers and A records are the same"
No. Nameservers determine where the DNS zone is managed. An A record within this zone determines which IPv4 address a domain points to.
What should you do before a DNS change?
- Note down the existing DNS records.
- Check if email services are affected.
- Plan changes as far as possible outside of critical business hours.
- Lower the TTL well in advance for planned migrations, if possible.
- Ensure that the new hosting is already prepared.
- Only delete old services once the migration has been successfully completed.
When should CURIAWEB support be contacted?
Contact CURIAWEB support if you are unsure which DNS zone is authoritative, if the domain still does not point correctly after a long waiting time, or if the website and email are affected at the same time.
The following information is helpful:
- Affected domain,
- Which DNS records were changed,
- Time of the change,
- Old and new target value,
- Information on whether nameservers were changed,
- Whether external mail services such as Microsoft 365 or Google Workspace are used.
Frequently asked questions about DNS propagation
Can CURIAWEB speed up DNS propagation?
Only to a limited extent. If external caches have saved old data, they must expire. However, CURIAWEB can check whether the DNS records are set correctly.
Why does the domain work via mobile data but not via Wi-Fi?
Both networks probably use different DNS resolvers. One already has the new information, the other does not.
Why does my domain still point to the old website?
Possible causes are DNS cache, wrong A record, wrong nameservers, an old AAAA record, or an incorrectly set up document root.
Can I test DNS changes immediately?
Yes, but the result is not always globally representative. Use multiple tests and check which nameservers are authoritative.
Register a new domain
If you need a new domain for your website, email, or another project, you can check and register your desired domain directly with CURIAWEB. This makes it particularly easy to manage domains, DNS, and hosting together.
