Depending on your dns cache google.tn will resolve, but the root authoritative nameserver was down for a bit and is sending bad responses.
You can also try gov.tn
I get authoritative answers for google.tn which say to use the same google's name servers for .com (ns1 - ns5).
Do you have a specific record under .tn that is not resolving? I am testing against the .tn name servers.
tn. 86400 IN NS ns1.ati.tn.
tn. 86400 IN NS ns2.nic.fr.
tn. 86400 IN NS pch.ati.tn.
tn. 86400 IN NS ns-tn.afrinic.net.
tn. 86400 IN NS ns2.ati.tn.
tn. 86400 IN NS rip.psg.com.
Depending on your dns cache google.tn will resolve, but the root authoritative nameserver was down for a bit and is sending bad responses.
You can also try gov.tn
I get authoritative answers for google.tn which say to use the same google's name servers for .com (ns1 - ns5).
Do you have a specific record under .tn that is not resolving? I am testing against the .tn name servers.