{"id":363,"date":"2022-02-05T18:28:58","date_gmt":"2022-02-05T18:28:58","guid":{"rendered":"https:\/\/exampracticetests.com\/aws\/DevOps_Engineer_Professional_DOP-C01\/aws-devops-engineer-professional-dop-c01-question351\/"},"modified":"2022-02-05T18:28:58","modified_gmt":"2022-02-05T18:28:58","slug":"aws-devops-engineer-professional-dop-c01-question351","status":"publish","type":"post","link":"https:\/\/exampracticetests.com\/aws\/DevOps_Engineer_Professional_DOP-C01\/aws-devops-engineer-professional-dop-c01-question351\/","title":{"rendered":"AWS DevOps Engineer Professional DOP-C01 &#8211; Question351"},"content":{"rendered":"<div class=\"question\">Your system uses a multi-master, multi-region DynamoDB configuration spanning two regions to achieve high availablity. For the first time since launching your system, one of the AWS Regions in which you operate over went down for 3 hours, and the failover worked correctly. However, after recovery, your users are experiencing strange bugs, in which users on different sides of the globe see different data.<br \/>\nWhat is a likely design issue that was not accounted for when launching?<br \/><strong><br \/>A.<\/strong> The system does not have Lambda Functor Repair Automatons, to perform table scans and chack for corrupted partition blocks inside the Table in the recovered Region.<br \/><strong>B.<\/strong> The system did not implement DynamoDB Table Defragmentation for restoring partition performance in the Region that experienced an outage, so data is served stale.<br \/><strong>C.<\/strong> The system did not include repair logic and request replay buffering logic for post-failure, to resynchronize data to the Region that was unavailable for a number of hours.<br \/><strong>D.<\/strong> The system did not use DynamoDB Consistent Read requests, so the requests in different areas are not utilizing consensus across Regions at runtime.<\/div>\n<p><\/p>\n<style> .hidden-div{ display:none } <\/style>\n<p>\t\t\t\t\t\t\t<button onclick=\"getElementById('hidden-div').style.display = 'block'\"> Show Answer <\/button> <button onclick=\"getElementById('hidden-div').style.display = 'none'\">Hide Answer<\/button><\/p>\n<div class=\"hidden-div\" id=\"hidden-div\"><span style=\"\"><\/p>\n<div class=\"answer\">Correct Answer: <strong>C<\/strong><\/div>\n<p><strong>Explanation:<\/strong> <\/p>\n<div class=\"explanation\">\nExplanation:<br \/>\nWhen using multi-region DynamoDB systems, it is of paramount importance to make sure that all requests made to one Region are replicated to the other. Under normal operation, the system in question would correctly perform write replays into the other Region. If a whole Region went down, the system would be unable to perform these writes for the period of downtime. Without buffering write requests somehow, there would be no way for the system to replay dropped crossregion writes, and the requests would be serviced differently depending on the Region from which they were served after recovery.<br \/>\nReference: <a href=\"http:\/\/docs.aws.amazon.com\/amazondynamodb\/latest\/developerguide\/Streams.CrossRegionRepl.html\" title=\"External link\" rel=\"nofollow noopener\" target=\"_blank\">http:\/\/docs.aws.amazon.com\/amazondynamodb\/latest\/developerguide\/Str&#8230;<\/a><\/div>\n<p><\/strong><\/span> <\/div>\n","protected":false},"excerpt":{"rendered":"<p>Your system uses a multi-master, multi-region DynamoDB configuration spanning two regions to achieve high availablity. For the first time since launching your system, one of the AWS Regions in which you operate over went down for 3 hours, and the failover worked correctly. However, after recovery, your users are experiencing strange bugs, in which users [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[2],"tags":[3,354],"class_list":["post-363","post","type-post","status-publish","format-standard","hentry","category-aws-devops-engineer-professional-dop-c01","tag-aws-devops-engineer-professional-dop-c01","tag-question-351"],"_links":{"self":[{"href":"https:\/\/exampracticetests.com\/aws\/DevOps_Engineer_Professional_DOP-C01\/wp-json\/wp\/v2\/posts\/363","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/exampracticetests.com\/aws\/DevOps_Engineer_Professional_DOP-C01\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/exampracticetests.com\/aws\/DevOps_Engineer_Professional_DOP-C01\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/exampracticetests.com\/aws\/DevOps_Engineer_Professional_DOP-C01\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/exampracticetests.com\/aws\/DevOps_Engineer_Professional_DOP-C01\/wp-json\/wp\/v2\/comments?post=363"}],"version-history":[{"count":0,"href":"https:\/\/exampracticetests.com\/aws\/DevOps_Engineer_Professional_DOP-C01\/wp-json\/wp\/v2\/posts\/363\/revisions"}],"wp:attachment":[{"href":"https:\/\/exampracticetests.com\/aws\/DevOps_Engineer_Professional_DOP-C01\/wp-json\/wp\/v2\/media?parent=363"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/exampracticetests.com\/aws\/DevOps_Engineer_Professional_DOP-C01\/wp-json\/wp\/v2\/categories?post=363"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/exampracticetests.com\/aws\/DevOps_Engineer_Professional_DOP-C01\/wp-json\/wp\/v2\/tags?post=363"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}