Question: how to do nslookup for multiple hostnames?
Answer: C:\Temp\Hostname.txt.
Example shown below:
www.google.com.
portal.azure.com. ... 
Open PowerShell as Administrator and run the below command to do the nslookup for the hostname in the text file.
To Save the output in text file:
Get-Content C:\Temp\Hostname.txt | foreach {nslookup $_} >> C:\TEMP\nslookup.txt.