Before running OCP-73203, there wasn't the load balancer ip 10.42.0.2,
After running it, it was present when show router-default service

    1. when the microshift cluster was ready, there were load balancer ips(10.1.235.103,10.44.0.0,192.168.124.212) for router-default service.
% oc -n openshift-ingress get svc
NAME                      TYPE           CLUSTER-IP     EXTERNAL-IP                              PORT(S)                      AGE
router-default            LoadBalancer   10.43.145.9    10.1.235.103,10.44.0.0,192.168.124.212   80:32207/TCP,443:31419/TCP   9m25s
router-internal-default   ClusterIP      10.43.13.246   <none>                                   80/TCP,443/TCP,1936/TCP      9m25s
    2. run OCP-73203(MicroShift] configuring listening IP addresses and listening Ports)
 % ./bin/extended-platform-tests run all --dry-run | grep 73203 | ./bin/extended-platform-tests run -f -

    3.  check the router-default service again, there were 4 load balancer ips: 10.1.235.103,10.42.0.2,10.44.0.0,192.168.124.212. 10.42.0.2 was added unexpected.
% oc -n openshift-ingress get svc
NAME                      TYPE           CLUSTER-IP     EXTERNAL-IP                                        PORT(S)                      AGE
router-default            LoadBalancer   10.43.145.9    10.1.235.103,10.42.0.2,10.44.0.0,192.168.124.212   80:32207/TCP,443:31419/TCP   46m
router-internal-default   ClusterIP      10.43.13.246   <none>    

    4. debug node and check its host's ips, and lists the files under /etc/microshift folder
% oc debug node/localhost.localdomain 
Starting pod/localhostlocaldomain-debug-ljjs8 ...
To use host binaries, run `chroot /host`
Pod IP: 10.1.235.103
If you don't see a command prompt, try pressing enter.
sh-4.4# chroot /host
sh-5.1# ip address | grep "inet "
    inet 127.0.0.1/8 scope host lo
    inet 10.1.235.103/24 brd 10.1.235.255 scope global dynamic noprefixroute ens3
    inet 192.168.124.212/24 brd 192.168.124.255 scope global dynamic noprefixroute ens4
    inet 169.254.169.2/29 brd 169.254.169.7 scope global br-ex
    inet 10.44.0.0/32 scope global br-ex
    inet 10.42.0.2/24 brd 10.42.0.255 scope global ovn-k8s-mp0
sh-5.1#

sh-5.1# ls /etc/microshift/
config.yaml.default  lvmd.yaml.default	manifests  manifests.d	ovn.yaml.default
sh-5.1#

One more ip address was present after running the case    

the load balancer ips should be as same as before