linuxtest.net.		30 IN SOA ns1.sdsns.com. nameserver.sds.co.kr. (
				2010072610 ; serial
				3600       ; refresh (1 hour)
				300        ; retry (5 minutes)
				604800     ; expire (1 week)
				3600       ; minimum (1 hour)
				)

linuxtest.net.		30 IN TXT "v=spf1 ip4:121.189.61.0/24 ~all"

Name servers:
linuxtest.net.		30 IN NS ns1.sdsns.com.
linuxtest.net.		30 IN NS ns2.sdsns.com.