Dynamic DNS not updated immediately

I am using a dynamic DNS client to update my BIND9 for dynamic IP client. The problem is that after the server accepted the request, it takes minutes to update the entry. How could I make BIND update immediately? The following is my host entry

$ORIGIN .
$TTL 38400 ; 10 hours 40 minutes
ddns.mydns.com IN SOA ns1.mydns.com. christopher.skywidetech.com. (
1223137975 ; serial
10800 ; refresh (3 hours)
3600 ; retry (1 hour)
604800 ; expire (1 week)
38400 ; minimum (10 hours 40 minutes)
)
NS ns4.mydns.com.
$ORIGIN ddns.mydns.com
$TTL 10 ; 10 seconds
mycomputer A 220.232.214.2

What does the named.conf file look like for this dynamic updated zone?