Hi @mrshenli,
oh. This may be the problem. In the new servers (10.1.1.101 & 10.1.1.102), getent hosts hostname returns nothing.
I am also testing the torch.distributed with some old servers in my lab now and they can work. In one of the old servers, it does return IPs currently in use.

Where I am using 10.0.1.101 and 10.0.1.102 for testing the torch.distributed (old servers).
I will figure this out in the new servers and let you know! Thank you!
Best,
Ziyi