You might have noticed that once you change a DNS record inside PressDNS or another DNS provider, it seems to take some time for it to actually take effect. Here’s why.
Understanding What DNS Does
To better understand how DNS works, you first need to understand what it actually does. Let’s break it down.
Everything on the internet has an IP address to know where it’s located. Without those IP addresses, the internet as we know it simply doesn’t work. To break things down even further, let’s think of the IP address like a GPS location.
Let’s assume you just bought a new house. How would your friends find your new place? Would you give them GPS coordinates? Unless you live in a completely remote location or are a total weirdo, you wouldn’t give them GPS coordinates. You would give them your address.
The same goes for websites. Would you want to remember a bunch of different IP addresses? Of course not. You just enter something like google.com into your web browser and you’re searching for what you need.
Just like mailing addresses translate a GPS location to a geographical location, a domain translates a readable name to an IP address.
In this sense, you can think of DNS records like entries in a phone book. By entering your website address into your browser, that address is translated into an IP address by using DNS.
So Why Does DNS Propagation Take Time?
When you update a DNS records, your DNS zone file is updated immediately, but your ISP might not have checked for updated information yet.
Each time you visit a website, your ISP will check it’s cache to see if a record already exists. If it does, it’ll use the cached location.
Because of this cache, it might take some time for your DNS to propagate. As soon as their cache expires, they’ll check the DNS zone again. If there are any changes, that’s when you’ll see your updated DNS changes take effect.
As every ISP is different, how long they cache DNS records can vary. Generally, your DNS changes should be rolled out worldwide within about 48 hours.