Unable to access cluster IP address from outside network

Description

There is no response when you try to access the cluster IP address from outside the network.

Corrective action

Verify that you can use ping to access the dedicated IP addresses of the cluster host from a computer outside the router. If this test fails and you are using multiple network adapters, the issue is not related to Network Load Balancing (NLB). If you are using a single network adapter for the dedicated and cluster IP addresses, consider the following scenarios:
Scenario Solution
If you are using multicast support, you might find that your router has difficulty resolving the primary IP address into a multicast media access control (MAC) address by using the Address Resolution Protocol (ARP) Verify that you can use ping to access the cluster from a client on the cluster's subnet and the cluster host's dedicated IP address from a computer outside the router. If these tests work properly, the router is probably at fault. You should be able to add a static ARP entry to the router to circumvent the issue.
When using NLB in multicast or unicast mode, routers need to accept proxy ARP responses (IP-to-network address mappings that are received with a different network source address in the ethernet frame). You must ensure that that your router has proxy ARP support turned on. You can also set a static ARP entry to keep proxy ARP support disabled in the router.
Internet control message protocol (ICMP) to the cluster is blocked by a router or firewall. Allow ICMP traffic through the router or firewall.

However, allowing ICMP traffic through router or firewall might expose your system to additional security risk.