If you are facing the issue Failed: DNS error: Host unknown .
- Check wheather your sitemap is valid or not. Check here
- if you are getting this error you have to add the domain name with https in property. If you add a naked domain , actually it would redirect to the https first and then dns. And DNS verification may not be occur due to security reasons. So better to add your domain in URL prefix session as https://knowledgeassam.com instead of knowledgeassam.com in domain section. See the below picture and add your domain in URL section of search console.
What is sitemap?
Sitemap is file where the metadata or information about the pages and post of the website is available. Sitemap is blueprint for a website. When Google crawl the website it's used to find details of the website in the sitemap. It helps search engine to find your website and indexed your post in the search engines. Eg knowledge Assam has a website called knowledgeassam.com and it's sitemap would be knowledgeassam.com/sitemap.xml and knowledgeassam.com/sitemap-pages.xml . Using these sitemap Google retrieve the information of the website.
Why is it important?
It's important because without sitemap it will not rank your website in Google. Moreover to get organic views and SEO friendly website you have to make sitemap.