This morning I was finalizing the my vCenter Appliance configuration and realized that something stopped working. For some reason, I could not open the console of a VM using vCenter.
If I were to login directly on host, then I would have no issues opening the console of the VM. I started looking around the on the web as to what it could be, some suggestions implied to make sure and have ports TCP 902/903 open. In my case, I knew they were open since this is in my lab and I don’t have anything out of the ordinary configured to block those ports. But to be sure, I tested this theory. I went a head and tried telneting on to the ESXi host on port 902
As you can see in the image above, was able to successfully telnet on port 902. Once I’ve gotten that out of the way, I was able to rule out the “port rule blocking” in my lab. Then I realized something. Unlike before, when I added my host to vCenter, I used a DNS name, rather than an IP. Because my management PC is not on the domain and doesn’t have the right DNS server settings configured for that domain, I could not ping the host by name. So to get around that, I added two entries in the hosts file so that I could resolve the host IP using its name.
I then went back to vCenter and tried launching the console again. At this point I was able to successfully open. DNS plays an important part in vCenter and it is important to make sure we have it setup correctly or else we can experience issues that otherwise can be avoided.