bind recursive dns server fail to answer for specific domain

I have bind9 dns server with resursion enabled only for internetwork. It is working normally but for one particular site it fails to provide the answer

"ipay.com.np"

When i do

dig @mydns.server.com ipay.com.np +trace 

it can fetch the answer. But normal dns query without other options does work

dig @mydns.server.com ipay.com.np 

; <<>> DiG 9.9.5-3ubuntu0.8-Ubuntu <<>> @202.94.66.2 ipay.com.np
; (1 server found)
;; global options: +cmd
;; connection timed out; no servers could be reached

Update:- now the records for domain ipay.com.np is fetched by my caching dns automagically. I havent done any thing but restarted bind server yesterday and now it works