how to verify sub-domains

[Amit Kucheriya]

In Site Administration > Authentication > Domains section -- I have added a domain and verified it (@example.com).

We also have some users who use email addresses with sub-domain like this (@tw.example.com). Question is I can add this sub-domain in the Domains section, however I am never able to verify it. I am using DNS method for both the verifications. I do see that the TXT string is the same in both cases. 

A followup question will be if sub-domain is not necessary to add explicitly, then would "Reset passwords now"  button trigger a password reset for users which have email address from sub-domain

[Charlie Misonne]

You will have to verify the subdomain as well.

So 1 TXT record for the main domain and 1 TXT record for the subdomain in your DNS settings. If the string is the same that's OK but you need both TXT records. Is that not working?

On Verify a domain to manage accounts  you will read verification of each subdomain is necessary.