Why does telnet not return -EINVAL for IP Address 0.x.x.x anymore?

Issue

• When trying to telnet a port to a 0.x.x.x IP address ,the kernel will check the if the IP Address is valid or not, instantly returning an error. However, on RHEL 9.1 the same telnet command will just try to make a connect regardless.

Using 0.1.1.1 as an example.

• RHEL8

$ telnet 0.1.1.1
Trying 0.1.1.1...
telnet: connect to address 0.1.1.1: Invalid argument

• RHEL9

$ telnet 0.1.1.1
Trying 0.1.1.1...
telnet: connect to address 0.1.1.1: Connection timed out