What does this iptables rule's options mean?

Question

The rule is

-A KUBE-SEP-G3HEJMIUHDVUA2GR -p udp -m comment --comment "kube-system/kube-dns:dns" -m udp -j DNAT --to-destination :0 --persistent --to-destination :0 --persistent --to-destination 

which is part of a kube service rule:

-N KUBE-SEP-G3HEJMIUHDVUA2GR
-A KUBE-SEP-G3HEJMIUHDVUA2GR -s 10.233.64.2/32 -m comment --comment "kube-system/kube-dns:dns" -j KUBE-MARK-MASQ
-A KUBE-SEP-G3HEJMIUHDVUA2GR -p udp -m comment --comment "kube-system/kube-dns:dns" -m udp -j DNAT --to-destination :0 --persistent --to-destination :0 --persistent --to-destination 

As I know normally this rule would have a specific destination like this one:

-A KUBE-SEP-XEZU3EBQ2WW4MLUB -p tcp -m comment --comment "default/nginx:https" -m tcp -j DNAT --to-destination 10.233.116.87:443

while the first one don't have a specific desitination which might because this service has only one endpoint, but I want to know:

1. What does the destination ":0" mean?
2. Why "--destination" appears three times?
3. What is the use of "--persistent" here?
4. Where can I find more detailed document about DNAT target?

Answer 1

This exactly is not an anwser. After digging more, I found the iptables rules in kube-proxy container are different from iptables rule on host machine.

 -N KUBE-SEP-OYL6BTTAC4W4HXLZ
-A KUBE-SEP-OYL6BTTAC4W4HXLZ -s 10.233.64.38/32 -m comment --comment "kube-system/kube-dns:dns" -j KUBE-MARK-MASQ
-A KUBE-SEP-OYL6BTTAC4W4HXLZ -p udp -m comment --comment "kube-system/kube-dns:dns" -m udp -j DNAT --to-destination :0 --persistent --to-destination :0 --persistent --to-destination

(the name and ip changed because I reboot my machine)

Then I checked the versions of both iptables cli and found they are not mached. I upgraded the kernel before, this might cause some problems. But I don't want to dig more, I'm not an expert of kernel.