Operations

Let's analyze the dashboard indicators to identify the root cause of the latency issues:

Key Findings from the Dashboard:
1. Service-to-service latency increased by 340% during business hours
2. Sidecar proxy CPU utilization is at 92% (very high)
3. Policy evaluation throughput dropped dramatically from 15,000 to 2,100 evaluations per second (86% decrease)
4. mTLS handshakes are completing successfully (not the issue)
5. Network interface utilization is only 28% (not the bottleneck)
6. Envoy proxy connection pool has 45% capacity remaining (not exhausted)
7. Distributed tracing shows authorization policy enforcement adds 890ms to each request

Root Cause Analysis:
The data clearly points to the policy evaluation and authorization layer as the bottleneck. The policy evaluation throughput has dropped by 86%, and the tracing data confirms that authorization policy enforcement is adding 890ms of latency per request. This is the primary contributor to the 340% latency increase.

The correct optimization is to scale the policy enforcement infrastructure and review the complexity of authorization policies. This addresses the control plane performance bottleneck that is causing the significant latency in policy evaluations.

Why Other Options Are Incorrect:

• Increasing network bandwidth is unnecessary because network utilization is only at 28%, indicating the network is not the bottleneck.

• Expanding certificate authority infrastructure and adjusting mTLS rotation is not needed because the dashboard shows mTLS handshakes are completing successfully. Certificate handling is not causing the latency.

• Deploying additional sidecar proxy replicas and increasing connection pool limits would not solve the issue. While sidecar CPU is high, this is a symptom of the policy evaluation overhead, not the cause. The connection pool still has 45% capacity available, and adding replicas would not address the control plane policy evaluation bottleneck that the tracing data identifies as the actual source of the 890ms delay.

The correct answer states that the tracestate header has a maximum size limit, and intermediaries may truncate entries from the end while preserving the most recently added vendor data at the beginning.

According to the W3C Trace Context specification, the tracestate header has a maximum size limit of 512 bytes (or 32 list-members, whichever is reached first). When this limit is exceeded, the specification mandates that intermediaries should truncate entries from the right side (end) of the list while preserving entries at the left side (beginning). This design ensures that the most recently added vendor-specific data, which is prepended to the beginning of the tracestate header by each participating service, is preserved during propagation.

The second answer is incorrect because the W3C Trace Context specification does not require registration of vendor identifiers. Vendors can use their own keys as long as they follow the specified format rules. There is no central registry that validates vendor identifiers.

The third answer is incorrect because the tracestate header does not implement any time-based expiration policy. The specification does not include provisions for automatically removing entries based on propagation delay or timestamp values.

The fourth answer is incorrect because while there is a maximum entry count (32 list-members), the truncation is not based on alphabetical ordering of vendor keys. The specification clearly states that truncation should occur from the end of the list, preserving the order in which entries were added, with the most recent additions at the beginning being preserved.