dns master <> slaves updating

hi people,

i see there is something wrong in my configuration.When i modify my dns through whm and i do the online test at this site then my slaves do not have the most recent information i modified.The dns server under my control is setup to be the master and i have two slaves (provided by my dedicated host)i get two warning in the online test.

i have been working on this for two days now google refuses to help me let's start by problem one

how do i make sure all my dns slaves download the latest dns zone file from the master ?

this must be a newbie question and yes i'm new to dns servers i just can't find out ....

why does the online test warns me i have no SPF record while the record is in my zone file ?

Code:

delphiprogramming.be 14400 IN TXT "v=spf1 a mx ptr include:telenet.be ~all" 

telenet.be is my internet service provider i have to send mail through there smtp servers

every time i edit my dns zone through whm i have to downgrade the serial number by one or the master and the slaves have different serial numbers this is a little annoying ....

help !

 

hmmm anybody alive around here i don't feel for paying my host $15 to get the issue resolved you know