Exam 70-741 topic 1 question 65 discussion

from what I understand and I may be corrected. The first connection Server 2 is going to make is to Server 1 on port 80. It will then get translated to port 84/ the container because it resides inside of Server 1.

For me, Answer is B. Server 2 can't know container IP and port in Server 1.

A key element to this question that is easy to overlook is that port mapping is already set up.

This is a 740 question. the Answer B is correct.

Pretty straight forward port mapping question. The Port mapping is set up to transfer traffic sent to Server 1 on port 80 to Container 1 on port 84. Therefore... Server 2 will contact Server 1 (Via it's IP address 192.168.1.78 on port 80) Server 1 will use the port mapping to transfer that traffic to Container 1 on port 84.

Answer is Correct

Got it. So basically using the host’s IP of the container (192.168.1.78) but going further and using port 80 since that’s the port the container is assigned to.

@Paz great info. As the access is from another device on the network, not the host providing NAT does this still apply?

https://techcommunity.microsoft.com/t5/Virtualization/Windows-NAT-WinNAT-Capabilities-and-limitations/ba-p/382303 Accessing internal endpoints directly from the Host: Internal endpoints assigned to VMs or containers cannot be accessed using the external IPs / ports referenced in NAT static port mappings directly from the NAT host. From the NAT host, these internal endpoints must be addressed directly by their internal IP and ports. For instance, assume a container endpoint has IP 172.16.1.100 and is running a web server which is listening on port 80. Moreover, assume a port mapping has been created through docker to forward traffic from the host’s IP address (10.10.50.20) received on TCP port 8080 to the container endpoint. In this case, a user on the container host cannot directly access the web server using the externally mapped ports. e.g. A user operating on the container host cannot access the container web server indirectly on http://10.10.50.20:8080 . Instead, the user must directly access the container web server on http://172.16.1.100:80 .

Microsoft has a known issue where if you connect from the same subnet as the server hosting the container then the container IP will not work. The 70-740 exam has multiple test questions around the same topic. If you had a container or server on the 172.16.5 subnet then it would be able to see and use the container ip\port. coming from the 192, only the 192 ip and port will work. hope this helps.

I am not sure, why the answer is B. Can someone please explain?