did you look my fotos?, at my reply #13
this happen someday sometime, the server was working.
if you look the fotos, if i do nslookup google.com my server response on 127.0.0.1
if i try nslookup webmail.analyze.com.mx 127.0.0.1 SERVFAIL and then try another dns like 192.168.1.254 or 8.8.8.8 or anyone you add.
but my clients has only 1 DNS my server DNS that it is 127.0.0.1 or his IP on the internal interface.