shell:$ nslookup -timeout=2 -retry=1 'mtn.ir'
;; Got SERVFAIL reply from 75.98.161.224, trying next server
;; Got SERVFAIL reply from 69.39.86.5
Server:		69.39.86.5
Address:	69.39.86.5#53

** server can't find mtn.ir: SERVFAIL