mail1.iforex.com has no NS records.
NS records for this zone are defined at iforex.com.
NS records for this zone are defined at iforex.com.
Question and response
Question
dig mail1.iforex.com. NS
Answer
The response has no answer records.
Authority
iforex.com. 86400 SOA pdns73.ultradns.com. info.iforex.com. 2013101952 10800 3600 2592000 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0