What is a DNS refresh?

Question

Recently a community website that I use went down and the admin stated that it would be 24 hours or so for some people in city to use the website due to the ISPs having to do a DNS refresh, or something along the lines of that.

Actually, here's what he said:
"Everything is done, so the site will be back online as soon as your Internet Service Provider does a DNS refresh. Some people can already see the site, for others it will be up to 24 hours or so."

Since this was posted last night I was able to access this website 3 or 4 times, but then I end up getting this message again. I don't understand how a DNS refresh works, and even so, why could I visit the site random times throughout the day, and then why does it keep going down again? It hasn't been up since this afternoon now, so now I'm concerned if this isn't ISP-based.

Any help would be appreciated,
Thanks.

Answer 1

DNS is Domain Name Service which enables you to type the name and it requests the website based on the IP number with that domain. So you don't have to type the number. If you know the IP of the site and its not shared hosting you can visit the site already if you want to type the domain you have to wait.
There is a DNS list of names and their numbers and it propagates through the internet. Whenever your ISP does its scheduled refresh it will request the list and any new changes with it so you can get to sites.

Answer 2

Every website has an IP address. For example, 64.233.187.99 is the IP address for google.com. In your web browser, you can go to a website by either entering the URL (e.g. www.google.com) or the website's IP address. I think you will agree with me that it is easier to remember and type in a website's URL. A DNS (Domain Name Server) is like the Yellow Pages for Internet addresses. You enter an URL address in your browser and the DNS server will search and find the corresponding IP address and take your browser to the desired webpage. Website's IP address can change without the URL address changing. It is the function of the DNS server to keep their listing uptodate (i.e. refreshed). So, even if there was a IP address change, you can type in the same URL and still be taken to the correct website.

In your case, the website's IP address changed; however, the DNS server is in the process of updating their listing. They still have the old IP address for the URL.

Answer 3

DNS is cached, so when you look up yahoo.com the DNS server goes out, looks up the IP address for yahoo.com and then saves it on the server for a certain amount of time depending on the DNS server. Usually it is less than 24 hours but most providers will advise to give it 24 hours for the update to take place.

Hard to say why you would randomly not be able to get on. you may want to do a yahoo search for nslookup, this may help you further troubleshoot the problem.