Server service dns priority

Hi, I’ve 1 master 3 backup and 6 slaves.
If I want to use only master and backup to offer services i’ve set like this:
service 0 100 port master
service 1 30 port backup1
service 2 30 port backup2
service 3 30 port backup3
service 4 10 port slave1
service 4 10 port slave2
service 4 10 port slave3
ecc ecc

Is it right?

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