Is it safe to flush DNS and what does it exactly do?


Is it safe to flush DNS and what does it exactly do?

In: Technology

You want to call your friend. You can’t remember numbers well so you have his number written down in your contact list so that its always accessible to you, said list has his name and since that is easy to remember, you just find his name on your contacts list and it gives you his number, quick and easy.

Sometimes this goes wrong though, for some reason you are not able to reach your friend, might be because he changed his number or something without telling you.

So at this point you delete his number from your contacts list and go to facebook where you know he publishes his number. It might have changed and if so, that solves your issue. If not, its likely something else causing a problem.

The DNS cache in this case is the contacts list, the name is the domain name (thing and the phone number is the IP address your computer needs to be able to contact that website ( Facebook here represents the general DNS server system. Your computer must convert into an internet address to be able to access it, sometimes the address changes or something happens that the local copy the computer has stored on it is no longer correct. Normally the computer itself figures out that it has to ask for it again from the DNS system, but sometimes it does it, so you manually delete your local copy of the DNS on your computer so that it forces your computer to fetch the IP addresses again.

Its perfectly safe to do.

Think of it like a phone. When you want to call someone, you’ll probably search up their name in your contacts list to find their phone number. This lookup process is basically what DNS (or Domain Name Service) does for the Internet. 

Imagine you’re on your computer and you open up a browser like Microsoft Edge, Google Chrome, or Mozilla Firefox. You type in the search bar and away you go. What happens behind the scenes is that your browser, takes that website you put in, and looks up an IP (Internet Protocol) address for that website. Think of an IP address like a phone number, it’s just a bunch of numbers put together that represent a particular computer on the internet somewhere. So your browser is looking up the number for a website, in a way that’s a bit different than you looking up the number for your friend in your contacts list, but the idea is the same. One of the main differences though, is that your contacts list is saved on your phone, and doesn’t change too often. Whereas with DNS, the IP addresses are more likely to change, and instead of saving all the addresses on your computer, a server (basically a computer somewhere) will either save the name/address for you, or ask another computer for the address if it doesn’t know about it yet.

One way to save time for this lookup process (since there are a ton of websites to look through), is for DNS servers to save a copy of the name/address temporarily after it finds it once. This is known as caching (pronounced “cashing”). Kinda like putting a friend’s number in your favourites list so that you can find it much faster next time. But since we visit so many websites, this list of names and addresses can get pretty long and more importantly, the information might become old or wrong. So you can do something called flushing the DNS server which basically means to clear all of those those name/addresses that it has saved in its temporary storage (or cache – pronounced “cash”). This means that any website you lookup after, will have to be looked up by the DNS server all over again. Almost like you’ve cleared your favourites list.

This is not the most accurate explanation but I tried to make it relatable in a way! As for safety, generally very safe to flush/clear your cache! In fact, in most cases, this will increase your safety online.

Edit: Missed answering part of the question – is it safe?