cant telnet to aix 5.2 and not even access through serial console

I have installed aix 5.2 on aix box through serial console connected to COM 1 . I even get a login prompt after the fresh installation . But as soon as i give a root & enter i again get a login prompt.i..e I am not able to logon after a fresh installation.
and even i configured IP configuration to get ip from DHCP server...through booting from CD1...now when i try to telnet that machine it says..

[root@ud-public test]# telnet 172.30.0.74
Trying 172.30.0.74...
Connected to 172.30.0.74 (172.30.0.74).
Escape character is '^]'.

Password required, but none set
Connection closed by foreign host.

Please help me