The correct option is Network Layer IP addressing and routing. After confirming that the physical cabling and the data link layer are operational the next layer to investigate in the OSI troubleshooting sequence is the Network Layer.

At the Network Layer you should verify IP address configuration, subnet mask, default gateway, ARP entries, and routing tables. Checking whether the host can reach its gateway and whether routers have the correct routes will determine if packets can be forwarded between networks and to the customer facing site. Misconfigured IP settings or routing problems at this layer are a common cause of connectivity loss once lower layers are verified working.

The option Cloud Load Balancing configuration can affect access to a website but it is not the immediate next step in the OSI layer sequence. Load balancing and application delivery are typically investigated after basic IP connectivity and routing are confirmed at the Network Layer.

The option Presentation Layer data encoding relates to how data is formatted or encrypted for applications and it resides at layer 6. That is higher in the stack so it is not the next thing to check after the physical and data link layers.

The option Session Layer connection state concerns session management between applications and it sits above the network layer. You should verify addressing and routing first before moving on to session state issues.

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