Cannot add to Domain

[enaugavule]

I've recently configured and setup a DC and AD account on Server 2019. Configured Hyper-V and ran AD, DC services and and also two other VM's for Windows XP and Ubuntu Desktop. This is a standalone setup and when I want to add windows XP and Ubuntu desktop on a the newly Domain created, it comes up with this error message below however I'm able to ping from server to clients and vice versa 

Please note I've tried the possible solutions below:

1. Turned off Firewall

2. entered the IP address static

3. Reset the Ad and DC server 3 times 

4. gone on other forums to find a solutions 

Appreciate if someone can assist 

[#2]

Ok.
1) Check PC is using DC DNS server DNS ip address as DNS server - (ipconfig /all)
2) Open command prompt on PC and type "nslookup <domainname>"... Does it resolve?
3) Open command prompt on PC and type "nslookup <doman fqdn>"... Does it resolve?

[#3]

@Dave Patrick THANK YOU SO MUCH FOR THIS!!!!!!

It Exactly went through without any issues!!!! AWESOME MAN!!!

Why do you think it causes these kind of issues?

[#4]

Glad to hear, you're welcome. Domain controller and all domain members must use the DC ip address for DNS so they can find and logon to domain.

please don't forget to mark best response 

[#5]

Why did you mark other post???

[#6]

sorry mate, mistakenly marked the wrong one
I've reverted it now to your fix :)

[#7]

thank you, much appreciated!