Google’s mobile-first indexing now powering over half of the web pages in Google Search results globally since it was introduced two years ago.
Mobile-first indexing uses Googlebot smartphone to crawl and index the mobile version of a web page.
Google revealing the state of its mobile-first indexing discussed the two most common that it sees when evaluating sites for mobile-first indexing.
As the company said before, only sites using a responsive web design qualify to move to mobile-first indexing.
And, once a site is moved, the site owners are notified through the Google Search Console.
Additionally, if a server log with the majority of smartphone Googlebot requests also confirms of a site’s move, or the URL inspection tool can be used to see how their site was last crawled or indexed.
Here is a screenshot of URL inspection tool show Googlebot smartphone:
Google says the following two issues might come up when a site is not responsively designed.
Structured Data Missing on Mobile Pages
Google advises using the same structured data on both desktop and mobile pages to help Googlebot better understand the content.
It’s because, with mobile-first indexing, Google will only use the mobile version of the page for indexing. Otherwise, it will “miss the structured data.”
Google advises webmaster to test their’s pages’ structured data for both versions and then compare the results.
For the mobile version, developers are advised to check the source code when simulating a mobile device.
Alternatively, the HTML generated using mobile-friendly testing tool can also be used.
Alt-text Missing in Images on Mobile Pages
The alt-attributes or (alt-text) helps users with screen readers as well as search engine crawlers understand the images.
As above, Google recommends checking “img” tags in a source code of the mobile version of the page.
To see a source of the mobile page either use the browser simulation tool or the Mobile-Friendly test for a Googlebot rendered version.
Then search the source code for “img” tags to ensure that the mobile page is providing appropriate alt-attributes, says Google.