networking – What does “ip4 default” mean in NetworkManager nmcli output?

My output of nmcli on my machine is as follows:

enp129s0f0: connected to enp129s0f0
        "Intel 82599ES SFI/SFP+"
        ethernet (ixgbe), 00:AB:50:C6:C4:D0, hw, mtu 1500
        ip4 default
        inet4 192.168.99.105/24
        route4 0.0.0.0/0
        route4 192.168.99.0/24

enp5s0f0: connected to enp5s0f0
        "Intel I350"
        ethernet (igb), 00:AB:50:C4:4C:1E, hw, mtu 1500
        inet4 192.168.11.14/24
        route4 192.168.11.0/24
        route4 0.0.0.0/0

What does the ip4 default portion of it mean? Why does it only exist on one interface?