Not able to ping my domain name

I’ve 2 main domains (bobu.xyz and y21.xyz) referring to the same droplet/ip address with ‘A’ records. But only bobu.xyz is working, y21 not.

Even I’m not able to ping y21.xyz thru windows command prompt. But when I check thru ‘whatsmydns.net’, I find that only 1 server is pointing to DO ipaddress, all others don’t point to any server at all. Why so?

I’ve set these name servers and ‘a’ records since 24 hours ago. I’ve not activated any firewall on my droplet yet. I’m able to ping the other domain ok. I’m able to ping both of my domains, thru my terminal/bash window, after logging into my droplet.

I’ve been writing to DO since one and half days, but they just correspond and kill time, nothing more. I see that the users just might be tired or have solved their problems thru google rather than keep waiting for them.