We provide free web hosting. (South Korea)

Having analyzed your recent activity (about 5 comments), i see, that you propagate just very brief posts

And in my humble opinion, your aim is just to promote that Kart service (as shown in the post scriptum-signature zone).
Earlier you have mentioned, that

But what for? - To use this decent ground to promote your services, not helping to other guys?

And if you read attentively my previous comments, i expected to get an illustrated example, describing the concept of dynamic dns - in relation to the servers' matters.

And also an additional purpose of this forum topic - to help that korean pal to improve his skills whilst studying

 

I am one of the oldest member of this forum and I do contribute a lot but it is fine with me for a newbie not to know me and easily come to such conclusion.

 

Probably, i was looking extremally rude, but...
what i had noticed from your previous activity, posts were almost useless; and your current post about ddns - is almost nothing, definitely not explaining any thing, what was sought for

right, i am a neophyte... and also i consider, your previous accomplishments do not entitle you behaving or being useless to people from this Forum (at a present time).

Take a look at Herr Till Brehm! - when i earlier asked for his assistance, he was extremally effective, helping solve the problem.

Over against, do you consider your reply satisfactory either complying with the spirit of this whole thread?

Am i wrong?

 

Do I understand correctly you're trying to run your own dns servers on a vps with a dynamic public ip?
Then you'll run into two problems.

First of all, when you create subdomains within your domainname that will be used as hostnames for your dns servers (NS records) you need to create glue records where you registred your domainname.
The glue records link your subdomains to the public ip('s) where your dns servers reside.
That's how the world gets to know where to find your dns servers (ip's) to query them about your domainname.
In theory you can supply a dynamic ip. But when that ip changes thegluerecors become invalid and your domainname will become undiscoverable until you update the glue records. So basically you should only use static ip's.

And second, you need a minimum of two dns servers.
But with only one public ip you can never connect to both from the internet.
With portforwarding you can link tcp/udp port 53 to one of the dns servers only.

Or wasn't this a case for that free web hosting?

 

If you read the opening post, you'll know he meant running a web server. He said:

By the way, I would ignore the other newbie here as he seems more a like spammer to me.