DNS lookup to public address

Coriron Haz
Coriron Haz used Ask the Experts™
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Hi all, I was wondering how to achieve the following:

Customers internal domain is company.local
I'm setting up a managed WiFi service for them. For this to work they need to be able to resolve the following:
http://unifi:8080 to my public cloud server which is located in an Azure instance.

I have created a CNAM dns record in my godaddy account for the following: ubnt.provider.tech

This resolves to the public IP address of the server, and i'm able to browse etc without any issues.

How do I configure the customers DNS server to resolve "unifi" to "ubnt.provider.tech" ?
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Brian MurphySenior Information Technology Consultant

Commented:
Coriron-
Is there a typo in there?

Public DNS consists of minimum two-dot.  So, ubnt.provider.tech the assumption is you own "provider.tech" domain name.

Based on the first example it would be unifi.provider.tech?

You cannot use a short-name unless your plan is to add hosts entries on all the Internet clients?

If the server is already public then it sounds like you want to host a web instance on that server that has the "host header" of "unifi.provider.tech"?

Just want to make sure I understand your question.
Coriron HazManaging Director

Author

Commented:
Hi Brian,

I was hoping to add a DNS entry into their DNS server that would translate the short name from unifi to ubnt.provider.tech (i own the provider.tech domain name)

Basically i'm setting up a ubiquiti solution, and by default it does makes an "inform" enquiry to http://unifi:8080/inform

You can use DHCP option 43 to point it to the IP address of your ubiquiti server, or apparently DNS to point "unify" to the IP address / FQDN of your server. This is what i'm trying to achieve. Does that help? (I can cange ubnt.provider.tech to unifi.provider.tech if it helps)
Assuming:

1. A Windows server is being used here, with an AD integrated DNS server.
2. The WIFI is setup to configure the clients to have the address of this server for DNS.
3. A connection specific DNS suffix is being used, which includes company.local

Then you will just need to add an CName record, on one of the clients DNS servers, stick it in the zone with all the other PCs.  This is pretty straight foreword.
Coriron HazManaging Director

Author

Commented:
Malmensa,

I had actually done this previously, but it wasn't working. I have since added the unifi.provider.tech cname into godaddy, and everything started working properly... i must have missed something somewhere. Nevermind! Thanks!
Brian MurphySenior Information Technology Consultant

Commented:
Thanks for the additional information.

It does raise more questions.

Is ubnt.provider.tech a valid server and have an IP address assigned?

DHCP can only do so much.  Your DNS servers must host this zone:

.provider.tech.

OR

They must have a forwarder or conditional forwarder for provider.tech.

Now, typical DNS query if you don't host that zone would forward to Internet.

The problem typically occurs with "split-DNS"

You could have an internal zone defined in DNS (not AD) that matches provider.tech.

That server might resolve to an internal IP of 10.10.10.5 (example only).

But if I am on the Internet it would resolve to a routable IP address that might be a NAT or VIP on a load balancer.

I think you said the server was accessible from the internet which did throw me off somewhat.

If it does have a routable IP address and your zone is external the answer is somewhat easier.

If you have an Internet accessible IP and you are doing some type of NAT to an internal IP and you have split-dns or split-brain-dns scenario where the zone exists internal and external the answer is somewhat more complicated.

If you only have external DNS and only an internet accessible IP address/server then somewhat easier.

Make sense?

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