N10-009 Question 112
Single answerTraffic flows: North-south, East-westA company hosts several application servers and database servers in its on-premises data center. Users from the internet access the public web application through the edge firewall, while the application servers also exchange large amounts of data with the internal database cluster over the LAN. During a security review, an administrator wants to identify which traffic should be classified as north-south versus east-west so the team can place monitoring tools appropriately. Which option correctly identifies the traffic flow types in this environment?
- A
Internet users connecting to the public web application are generating north-south traffic, while application servers communicating with database servers inside the data center are generating east-west traffic.
- B
Internet users connecting to the public web application are generating east-west traffic, while application servers communicating with database servers inside the data center are generating north-south traffic.
- C
Both the internet user traffic and the server-to-database traffic are north-south traffic because they ultimately support the same application.
- D
Both the internet user traffic and the server-to-database traffic are east-west traffic because they traverse switching infrastructure inside the organization.
Show answer and explanation
Correct answer: A
Explanation
In Network+ terminology and common enterprise network design practice, north-south traffic is traffic that moves into or out of a network, typically crossing a perimeter device such as an edge router, firewall, or internet gateway. East-west traffic is lateral traffic that moves between systems inside the network, such as server-to-server, workload-to-workload, or communication between internal segments and VLANs. In this scenario, internet clients accessing the web application are part of a north-south flow because the traffic crosses the organization's boundary. The application servers talking to database servers internally are part of an east-west flow because the communication remains within the organization's environment. This distinction matters operationally because perimeter controls often inspect north-south traffic, while internal segmentation, ACLs, and internal monitoring tools are commonly used to observe and restrict east-west movement, especially as recommended in zero trust and segmentation best practices.
- A. Correct.
Correct. North-south traffic refers to traffic entering or leaving the network, such as client connections from the internet to a public-facing service through the organization's perimeter. East-west traffic refers to lateral traffic moving within the internal network, such as communication between application servers and database servers in the same data center or across internal segments.
- B. Incorrect.
Incorrect. This reverses the standard definitions. External client traffic crossing the network boundary is north-south, not east-west. Internal server-to-server communication within the environment is east-west, not north-south.
- C. Incorrect.
Incorrect. Traffic classification is based on direction and network boundaries, not whether the traffic supports the same business application. External inbound or outbound communication is north-south, while internal lateral communication is east-west.
- D. Incorrect.
Incorrect. Although internal switching may carry some of the server-to-database traffic, internet user traffic crossing the edge of the network is still classified as north-south. The presence of switching infrastructure does not make all traffic east-west.