General Question for the DNS Gurus out there!

[BigLion]

Earlier today, I needed to change my “A” Record. Not unexpectedly, later in the day when I check the propagation on a DNS Checker site, some areas/servers still have the old record. However, I don’t understand this: about 6 servers say “Not Resolved.” The servers are not down or anything; if I test with other domains they resolve. I know I have to wait longer for everything to propagate, but WHY are some servers showing “Not Resolved” instead of the previous IP address?

[KangJL]

This??

What is DNS propagation

You’ve added a new domain name to your account, just changed your nameservers or recently modified some DNS settings. However, they aren’t working yet. You’ve discovered already that it’s not working yet because of something called “DNS Propagation”. But what does that mean? Introduction to DNS Before you can understand how DNS Propagation works, you need to understand how DNS itself works. So let’s start with that. Servers on the internet are identified by a set of numbers called an IP addres…

[BigLion]

That is a genuinely helpful and informative article, thank you! However, what I’m missing is that all the Domin Servers in the online DNS tool I’m using had the previous A Record resolved before. After I changed the A record, during propagation (as described in that article), some that haven’t propagated yet still contain the old value. THAT I understand. But, what would cause some servers to simply say “Not Resolved” instead of having the old value? If I’m missing something obvious, my apologies.

[KangJL]

This is expected. Due to the way how internet works, the dns resolvers are not all updated at the same time. If resolver is down, “not resolved” is a possible scenario.

[BigLion]

Thanks so much! Got it!
P.S. You derve a pay-raise!