In this article, we will explain the process of DNS caching and DNS propagation. Basically, the DNS Servers can take a bit long to propagate the information due to intermediary networks caching procedures.

The basics of DNS: what is DNS?

Every network device on the web makes use of an IP address to route your request to the site you’re trying to connect. This is similar to someone asking to the DNS server what is the IP address of a certain domain. Then, the DNS server answers this question, with the corresponding IP address. Whenever you type a URL and hit enter a request is made for a particular website, which is routed to a DNS resolver. The ISP (Internet service providers) manages this process. May it be a cable internet provider, a DSL broadband provider, or a corporate network.

The DNS resolver for the ISP forwards the request for a particular website to a DNS root name server. And once the DNS server holding the IP address for the requested website is found, it will answer with the corresponding IP address. Further, this IP address will be provided to your browser via your ISP.

Sometimes your ISP can’t find the IP address information locally. In this case, it forwards the query to other DNS servers in the world. The DNS servers will “talk” between them, in order to fetch the IP address information of a domain.

What is a DNS Cache?

DNS cache (also known as DNS resolver cache) refers to a process of storing data temporarily about the previous DNS lookups on the computer’s operating system or browser.

The DNS cache maintains a record (IP address) of all recently viewed websites and domains. Maintaining a cached copy of DNS lookups speeds up the process of data retrieval. Speeds up IP address resolution as well, by avoiding the need to go through the complete process of DNS lookup again.

DNS Propagation basics: How does it work?

Whenever you update or change the nameservers for a domain, it is likely to take 24-48 hours for the change to come into effect. This happens because all the ISP (Internet service provider) nodes across the world need to update their records often. They will fetch the new DNS information of your domain as well. This stipulated time period that is required for updating of new DNS/IP information is known as DNS propagation.

However, it has come to notice that, due to tremendous growth in technologies and speeding up of operational tasks the propagation time has been reduced by significant amounts. The above proposed time is ideal but in many cases, it may differ according to situations.



DNS Propagation time

The intermediary providers must update their DNS caches from time to time. They have to keep caches, in order not to overload the internet. The internet providers’ interconnection speeds have grown substantially over the last years. Consequently, DNS caching time has been reducing. In the middle ’90s, a domain name could take up to 3 days to propagate the DNS changes. Nowadays, we can see it in a few hours only. The following graphic explains the DNS propagation time, on average:

Is it possible to force DNS propagation?

DNS propagation is almost a natural factor, and each intermediary DNS server has its caching time. Whenever the caching time expires, it will query again the domain registrar to check for any updates in DNS. However, we can force our PC to look up again for the updated DNS. There isn’t really a method to force DNS propagation, but we can force our local PC to update it.

In Windows command prompt, this will flush your local DNS cache:

ipconfig /flushdns 1 ipconfig / flushdns

Or even, we can simply change our local DNS servers. This way there is a big chance to force the new DNS to update. We can recommend these free DNS resolvers:

Google DNS: 8.8.8.8 and 8.8.4.4

OpenDNS: 208.67.220.220 and 208.67.222.222

How to check DNS records

There are some free sites available, that checks your DNS records for free. In our opinion, the best DNS checker is the one from Mxtoolbox, as it usually offers a shorter DNS propagation times.

Is it possible to check the DNS propagation in Google?

This is a very common question from our customers. Using google search it’s impossible to notice DNS changes in a domain name. Thus, you can use Google DNS servers in your local PC, and this can speed up the DNS propagation time of your domain.

Google’s free DNS IPs are:

8.8.8.8

8.8.4.4

You should simply replace the local DNS server from your ISP with these IPs from Google DNS.

Conclusion

Firstly, DNS propagation may take from a while to several hours to complete. It’s becoming faster and faster over time. Finally, you can use Mxtoolbox to check for the DNS Propagation status. It’s a nice tool that will help you to check the current status of DNS propagation around the world.