Sometimes when you want to verify the domain ownership using TXT and CNAME records, you face challenges identifying why it taking lot of time for verification.
Normally it may take up-to 72 hours for TXT and CNAME records to propagate in DNS settings, but you can identify whether the changes you did has been reflected on not in public records.
This can be checked from using web based equivalent of Dig command using Google Admin ToolBox.
Check MX is an easy to use DNS validation tool that looks for common MX record misconfigurations.
Dig can be used as a web-based equivalent of the Unix dig command.
To check DNS and related records, open https://toolbox.googleapps.com/apps/dig/ and enter your domain name and click on the type of record you want to check.
For example, below image shows the TXT records for our this website.