I'm finding out how absolutely useless the Networking Module in my Hardware Engineering degree was.

I'm interacting with my ISP for a low bandwidth fixed IP. Their price is good, but I'm unclear about DNS. They're offering PTR DNS, I gather. Is that any use?

My isp has a block in the 83.x.x.x range, but they're offering me an address in the 92.51.x.x range which whois identifies as being of Russian origin. 92.51.x.x already has an A record (so says dig) as a.root-servers.net. Putting a.root-servers.net into nslookup gets me 198.41.0.4. Whois reports 198.41.0.4 as being some lot in Vancouver

I don't care, really. I just want to put up a small-time server with really low traffic and plenty of closed ports. And I'd like dns so my friends can find it fairly handy

That most likely means they'll let you update the PTR records for reverse DNS, so that if you lookup businesskid.ie and it resolves to 123.234.10.1 and then lookup 123.234.10.1 it resolves back to businesskid.ie

That's just one of the "root" DNS servers that allow the whole thing to work together, wouldn't be worried about that.

The days of XX.YY.xx.yy being country/region specific are pretty much over given the "horse-trading" of IP ranges between providers so it's unlikely to mean that much. If you'd dug a bit deeper you'd find that there are sections of 92.51.x.y delegated to providers in.... Russia, Moldovia, German, Greece, and Ireland.

Yes, I assume by PTR your ISP will provide a PTR DNS record. It associates an IP address with a FQDN.

You could always use a free dynamic IP service like noip.com which basically does the same thing without paying for a static IP address. A client runs on the host or even your router that updates noip.com with your public IP address. The domain ( i.e ddns.net ) is one provided by no-ip and they have several to choose from.

I make use of this, my router has an inbuilt client that updates a ddns.net host and (because I'm a nerd) I have a cname record in one of my own domains that points to the ddns.net record

Great idea, I never thought about doing that...

You've lost me. Mind you, I made a conscious decision to keep up with none of this stuff and be a luser, but now it appears I might have to actually learn some of it .

I'd totally forgotten about noip.com, ddns.net & co. Those sound like totally viable options if the fixed record doesn't work out.
Yes, Ireland is where I'm from. The cost for a static IP along with my service is a once-off €61.50, which is hard to resist. So, if they give me a PTR dns record and somebody down the road keys www.businesskid.ie in his windows or Android browser(presume the worst in browsers), will that resolve to me, despite the other records detailed in post #1?

EDIT: Personally, I'd never register an .ie address. You need a registered trade name or company with the same name to get an .ie domain name

Now that the pain of learning has started, what record(s) do noip.com or ddns.net give me?

I've had a .ie or two in my time and agree they are (to use an Irish phrase) a pain in the hole.

A PTR record is a reverse record not a forward record so you'd still need a domain name to access your IP.

Noip or ddns will give you something like businesskid.noip.com etc. But from memory you have to login regularly to avoid charges.

If you do register a domain name they are undr €10/year for a year.

look into what you can do in cloud computing. at least you can get lot of different IP addresses.

With noip.com for free you have to confirm you are still using the URL every 30 days or it will be automatically deleted.

Thanks, very much guys. No, a PTR record is not really what I want.It would be nice to have one, I'm sure; I'd feel kind of weird without one, but the majority of the access would be hostname-->IP.

I once got the Entire OS of a 1974 hardware testing box some guy was trying to revive. I was trying to help with his Electronic hardware problems. It was about a Meg in total. The biggest file was /etc/hosts, @200k.It had no dns at all. If you weren't in /etc/hosts, you didn't exist . Simpler Happy days. Now there's horse trading of IPs, Massive DDoS attacks, hackers inserting ransomware, blah, blah …

So, I got the 'final' reply back. It's just the PTR dns record. But I'll go with that, and use nioip.com, ddns.net or one of those, as I presume nobody with a browser will ever get back to me with just a PTR record.