Regression test IP binding?

[mzealey]

Just looking through the regression-tests.recursor README.md file and noticed it is talking about setting up some set of ips on the loopback interface. Why do you use 10.0.3.* rather than something like eg 127.0.3.* which on ubuntu linux at least is set up by default

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever