Focusing on Client Side Errors

Client-side errors

In a distributed system, clients often access the service via an HTTP request. We can monitor our web and application servers’ logs if a request fails to process. If multiple requests fail, we can observe a spike in internal errors (error 500).

Those errors whose root cause is on the client-side are hard to respond to because the service has little to no insight into the client’s system. We might try to look for a dip in the load (as compared to averages) but usually, such a graph is hard and it can have false positives and false negatives due to factors such as unexpectedly variable load or if a small portion of the client population is affected.

There are many factors that can cause failures that can cause clients not to reach the server. These include:

• Failure in DNS name resolution
• Any failure in routing along the path from the client to the service provider
• Any failures with third-party infrastructure such as middleboxes and content delivery networks (CDN).