DNS propagation overview

Overview #

DNS propagation is a way to describe the length of time it takes for the new DNS records to expire on your server. For instance, if you update your domain’s nameservers to point to a different company, then it’ll need time for those new records to propagate across the Internet. Every ISP has their own policies surrounding how often they update and expire their cached DNS records. These updates can take hours or days to propagate across the Internet as there is no one single standard.

Additionally, the term DNS Propagation is a rather inaccurate phrase used to describe how your network’s DNS changes are made. The word “propagation” implies that the change happens in a very specific manner, which isn’t true. You do have control over how quickly they happen. In fact, DNS servers will request the data from your local DNS server as and when it’s needed. These values are controlled by the administrator of your local DNS server and are set using ‘time to live’ (TTL) times.

This page provides details on DNS Propagation, DNS Caching, TTL and how to use the tools available to test whether a domain has been propagated properly.

Caching #

How DNS caching works #

With so many requests coming in from a DNS system, the designers wanted to find a way to reduce the burden on individual servers. So they devised a free and decentralized system to transfer domain name queries from one server to another across the Internet. It is for this reason that DNS caching can be viewed as an important aspect of any successful website. It allows users to save time by consulting the cached results of their queries.

Put simply, everyone’s DNS server gets cached locally. This allows your Domain Name System to work immediately without delay and without the need for a new query. DNS query. The TTL value has to be updated at some point, which is when the DNS needs to be updated.

Time to live (TTL) #

DNS responses are valid for a fixed period of time called the time to live (TTL). This is usually set by the administrator of the DNS server that hands out the response. It can be anywhere from an hour, to a day, to months.

Caching time #

Changes to DNS can take a few days to be global and full-effects. This has been explained through the following example: if an administrator changes the TTL of www.example.com from 6 hours to 12 hours, this will not happen immediately since the DNS is cached over 6 hours by default, meaning that a visitor accessing www.example.com after 2 days will still, it is essential that the admin knows that a person who cached a website with the old IP address at 12:00pm will not look it up again until 6:00pm. The time period between 12:01am and 6pm in this example is called the caching time. This begins when you change a DNS record and ends once the TTL expires.

With DNS records usually resolving within 1-12 hours, it’s important to remember that it can take time for the DNS changes to update on all devices in different locations. Even though the update may be visible on some computers in some locations earlier than others, the change will eventually be visible everywhere.

Numerous people make errors and reference a strange 48, 72 or sometimes 24 hour propagation time when they change their DNS settings. There might be a delay in when all DNS servers are updated with the information. This is because records are handled by the zone parent DNS servers (e.g. the .com DNS servers if your domain is example.com), which typically cache those records for up to 48 hours. However, it takes a few minutes for any DNS servers that have not cached them to receive the changes. And any DNS changes on your domain other than for the nameserver records and authoritative DNS server can be nearly instantaneous (You may lower the TTL in advance, and wait until the old TTL has expired before changing it.)

Adjusting Time To Live (TTL) #

Each website has a TTL value, which tells what the average amount of time is for it to be stored in memory on a web server. The default is about 4 hours.

It’s a good idea to drop the TTL as low as possible before initiating your domain transfer. This will speed up the transfer and allow you to change service providers in less time.

Flushing the DNS cache #

If you’ve made changes to your DNS recently, but don’t see them on your site, then you may need to flush your cache.

Please visit the following article to read more about how to clear your DNS cache:

This tool will show you the status of various DNS servers. #

Check the below tools to confirm in what locations your DNS has updated:

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