Having multiple preferred IPv4 addresses is normal and well-treated by the standards.
The inet family provides the capability to assign multiple addresses to each logical unit, with each address equally represented on the interface.
Here are some facts :
- Any network interface can have multiple addresses on a single logical unit.
- Each logical unit can only have one primary IP address, but multiple preferred addresses.
- A primary address is the local (source) address that is used when sending packets
from the computer to a destination address that is not local to any configured subnet.
- The preferred address is used when an interface has two addresses configured within the same subnet. The default selection of the preferred address is the lowest numerical prefix.
- If there is only one address, it is both primary and preferred.
- All addresses are allocated by the DHCP master or masters for the local network or networks, or are alternatively locally set as fixed in the interface.
Having multiple preferred IPv4 addresses is however not the normal situation.
The usual cause is the router, for example when splitting the network into the sub-segments
of main and guest subnets.
This situation can also be caused by the manual configuration of the local network,
or by simple inefficiencies in the router granting several leases to the same computer,
or by other local network architecture segmentation such as VPN to another computer
on the same network.
If having multiple preferred IPv4 addresses was not intentional,
it can normally be corrected by the release of all DHCP leases
and the renewal of only one lease.