why this article say This article is no longer maintained, so its content might be out of date. even after update?
Swarnava, that's because this article has been marked as "obsolete". That was a decision made some time ago. So the article may get updates, but it's not considered important anymore, so we don't give any guarantee that it still applies and we don't show it in search results.
This is one of the old "Navigation category" articles that used to be linked from one of the links in the old SUMO home page, /kb/home-page-ia-nav before the switch to the new Information Architecture (IA). Related discussion:
I think that Michael Verdi (or another admin?) marked all of these articles as "obsolete" en masse (without considering whether individual articles might still be useful) , when the switch to the new IA occurred last September.
Looking at this article, it's more than just a collection of links to other KB articles (the first four links are "external" links to Kaspersky and Norton web pages). If the article is still useful then the Description section should be revised ,to change it's category from "Navigation" to "Troubleshooting", to update the "Topics" section, and to remove the "obsolete" checkmark. (I'll let someone else decide whether to that.)