Where Does East-West Data Center Traffic Flow?

In a data center, data traffic that moves east-west is flowing between:

  1. the top-of-rack and distribution switches.
  2. the server and the cloud.
  3. the top-of-rack and core switches.
  4. top-of-rack switches. Source Reference Answer

Community Votes

D
100%

100% of anonymous learners picked answer D. Votes are pick records left by other test-takers — they are not the verified answer.

Community Insight

This question tests your ability to differentiate east-west (internal server-to-server) from north-south (external/client-to-server) traffic patterns, with the trap being confusion over which switch layer handles each flow.

East-west traffic refers to server-to-server communication within a data center, primarily routed through top-of-rack switches. Community consensus confirms that mastering these directional terms is critical for distinguishing internal workload communication from external north-south traffic.

Test-takers frequently select A or C, incorrectly assuming east-west traffic must traverse uplinks to distribution or core layers instead of staying local within the rack.

Community Discussion (4 comments)

a87d6a4 👍 2 Selected: D
In a data center, east-west traffic refers to data movement between servers within the same data center, often within or between racks. This traffic primarily flows through top-of-rack (ToR) switches, which connect servers within the same rack and facilitate communication between them. A. the top-of-rack and distribution switches: This typically describes north-south traffic, where data moves between the data center and outside networks or between different tiers within the data center. B. the server and the cloud: This describes traffic moving out of the data center to external locations like the cloud, which is considered north-south traffic. C. the top-of-rack and core switches: This involves traffic that moves between different layers of the data center network (such as from the ToR to the core switches), typically describing north-south traffic.
441fa70 👍 2 Selected: D
In a data center, data traffic typically moves through the following types: 1. North-South Traffic: - Definition: Traffic that flows into and out of the data center, typically between the data center and external networks, such as the internet or remote branch offices. - Examples: User requests from the internet to web servers, data replication between data centers, and remote backups. 2. East-West Traffic: - Definition: Traffic that moves laterally within the data center, between servers, storage systems, and other internal devices. - Examples: Communication between application servers, database queries from web servers to database servers, and data synchronization between storage systems. Understanding and managing these traffic types is crucial for optimizing data center performance, ensuring security, and maintaining efficient resource utilization.
1df8701 👍 2 Selected: D
D - East west relates to traffic between servers, which is through the top of rack switches
1df8701 👍 2
D - East west relates to traffic between servers, which is through the top of rack switches

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Expert Analysis

Why the Answer Is Correct

East-west traffic denotes horizontal communication between servers located in the same data center or rack. Top-of-rack (ToR) switches are specifically designed to aggregate this intra-rack and inter-server traffic before it potentially moves upstream. Therefore, traffic flowing between servers directly utilizes the ToR switching layer.

Why the Other Options Are Wrong

Options A and C describe traffic traversing uplinks to distribution or core layers, which aligns more closely with north-south traffic or aggregated backbone routing. Option B describes external-facing north-south traffic moving outside the physical data center boundary. These paths handle client requests or cross-datacenter replication, not localized east-west workloads.

Community Comment Notes

Multiple high-voted comments explicitly clarify the east-west versus north-south dichotomy, reinforcing that server-to-server communication stays within the rack infrastructure (Comment [2]). Comment [1] correctly identifies that movement between racks or to distribution switches often represents north-south or spine-leaf transitions rather than pure east-west flows. The consensus strongly supports D based on standard data center design principles (Comments [3], [4]).

Official Reference

Exam Strategy

Memorize the cardinal direction analogies for network traffic: north-south crosses the perimeter, while east-west stays inside the data center. Visualizing a traditional three-tier or modern spine-leaf topology will help you instantly map which switch tier handles which traffic type during the exam.

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