DNS - can any experts out there explain this ?

[#1]

Bear with me please if this seems a long post
First, the background...
I dont do anything clever with my PlusNet account, my mail is POP3 and my website ( for what it is! ) uses my PlusNet webspace. Recently, however, I have had the need to setup a remote support facility to help relatives with problems. I looked at various options ( logmein etc ) but didnt like the idea of third party servers being involved so decided to go down the UltraVNC route which I already use in the office to remotely login to servers etc. Using UVnc Single click means that I only need to do any portforwarding at my end so its nice and simple, apart from the need to make a connection to my Public IP address and this is where I started to get confused.
I guessed that I would need to use something like DynDns to get a hostname to point to my IP, since I assumed that <myusername>.plus.com would be pointing to the PlusNet servers. Then I remembered that some time ago ( when on 0808 dial up ) I had to have a static IP and sure enough I still did, ok I could use that, but not very nice to burn an IP into configuration files. Then accidentally I noticed that on my voip account status it said 'online from ip xxx.xxx.xxx.xxx ( <myusername>.plus.com ), heh! does that mean that <myusername>.plus.com resolves to my public ip, if so I can use that and not burn in an IP.
So a little checking with nslookup shows:-
<myusername>.plus.com resolves to my public ( static ) IP.
www.<myusername>.plus.com resolves to the PlusNet ( I assume webspace ) servers.
I also have a domain ( free one after the spam debacle ) hosted by PlusNet, so i checked that as well

<mydomain>.org.uk resolves to the PlusNet servers.
www.<mydomain>.org.uk resolves to the PlusNet servers.
Ok , still with me ? ( not got bored yet I hope ), I dont know a lot about the underlying technicalities of DNS so here's the questions.
1) how come <myusername>.plus.com can resolve to my public ip when both web hosting and email is handled by the PlusNet servers.
2) Can I setup my PlusNet hosted domain to operate similarly , possibly by configuring A records in the Domain admin section of the portal ?
Thanks for staying with me there, and any explanations would be appreciated.

[#2]

I'm certainly no expert, but ....
<myusername>.plus.net
www.<myusername>.plus.net
mail.<myusername>.plus.net
are three different addresses, so the DNS records for <myusername>.plus.net can point all three of them at different IP addresses. They point the first one at your static IP address, the second at plusnet's web servers & the third at plusnet's mail servers.
So your relatives can enter <myusername>.plus.net into UltraVNC & they will be knocking on the door of your router. Just as you do at work, port forwarding will then point the traffic to the appropriate PC behind your router.
If your second question is - could I host my other domain here at home? - then I don't see why not. Technically, the DNS record just needs changing to point to your IP address rather than that of plusnet's web server. I don't know if there are any other considerations or rules that apply to a plusnet supplied domain name.

[#3]

@Simon M, Thanks for the reply.

Quote

are three different addresses, so the DNS records for <myusername>.plus.net can point all three of them at different IP addresses

Ah, I hadnt realised that they were effectively different addresses , I had assumed that since the third level <myusername>.plus.com pointed at me how could any fourth level domain be different ? Now I appreciate.

Quote

So your relatives can enter <myusername>.plus.net into UltraVNC & they will be knocking on the door of your router

Yes thanks I've already done that and it works fine.

Quote

If your second question is - could I host my other domain here at home?

No It isnt , what my question is , can I point just the third level domain <mydomain>.org.uk at my IP and leave the fourth levels www. and mail. pointing at the PlusNet servers. If so how do I do it using the domain administration facility on the portal

[#4]

Quote from: MisterW

can I point just the third level domain <mydomain>.org.uk at my IP and leave the fourth levels www. and mail. pointing at the PlusNet servers.

Isn't that the current situation?

[#5]

@Simon M,
No , its ONLY like that for <username>.plus.com, for <mydomain>.org.uk EVERYTHING points to the PlusNet servers.
Hence my confusion, I sort of expected them to be the same...

[#6]

Ah - sorry, being thick. Yes. I see what you mean.
I wouldn't have thought it was a problem - I should raise a ticket & ask if it can be done. No, better still, raise a ticket & just ask for it to be done.
I would wait until the working week has started before raising the ticket.

[#7]

Quote from: MisterW

No It isnt , what my question is , can I point just the third level domain <mydomain>.org.uk at my IP and leave the fourth levels www. and mail. pointing at the PlusNet servers. If so how do I do it using the domain administration facility on the portal

Set up an A record using the advanced domain configuration controls on the portal. Something like this should be suitable:

home.mydomain.org.uk.                        A                    <your.home.ip.addy>

Remember the dot after the host name on the left-hand side. The right hand side needs to be your static IP address. The change will take 24-48 hours to fully propagate.

[#8]

@Bob, Thanks for that info , I'll give it a try.

[#9]

I didn't realise users had that level of control themselves on the main platform. I had thought that only came with PAYH. Not having any domains hosted with Plusnet, I don't have access to the domain configuration screens.
I needed to do fancy things with SRV records to run a SIP server on my own IP address (or at least, I needed someone else to do fancy things with SRV records - was way outside my comfort zone back on 2003 & I think I might still struggle), so I couldn't use Plusnet. PAYH could probably cope with it these days.
Now you see why I said at the start that I was no expert!

[#10]

Quote from: Simon

I didn't realise users had that level of control themselves on the main platform. I had thought that only came with PAYH. Not having any domains hosted with Plusnet, I don't have access to the domain configuration screens.

The level of control you have is limited. You can only set up A, CNAME and MX records and even so, certain things still require intervention from the support team.