One SEO pro had a question on images. They wanted to know about the importance of image file names for site ranking and images in web search in general.
They are using an intelligent CDN (content delivery network) provider, which has been replacing the image file names with unique numbers.
And they noticed that all the images are 404s in Search Console.
Disabling the CDN would significantly degrade overall site performance. So their question is: will image alt text and caption be sufficient for Google to understand, without an appropriate image, file name, and title?
John explained that there are two things he recommends looking at. The first is, if these are images that you need to have indexed in image search, then you should definitely make sure that you have a stable file name for your images.
That’s the most important element here.
Also, John pointed out that the SEO professional doesn’t mention that the numbers or URLs change. Sometimes the CDN essentially provides a session-based ID for each image.
And if the image URL changes every time Google crawls, then they will never be able to index these images properly.
This is mostly because for images, Google tends to be a bit slower regarding crawling and indexing. So if they see an image once, they say “Oh, we should take a look at this,” and then they try and crawl it again, then at some later stage the number has changed by then.
Then they will just drop that image from their search results from the image rankings. And they will just say “Oh: this image that we thought was there is really no longer here.”
John then explained that the most important part of figuring this out is: do you care about image search?
If so, you need to make sure that you have a stable URL for all of these images. It doesn’t matter if it’s a number, or if it’s text, or anything like that.
Just that the URL to the image is a stable URL. That’s the most important part here.
The other part that the SEO pro mentioned is the image alt text and captions, which suggests that they actually are interested in web search, and not necessarily image search.
For web search, Google doesn’t need to be able to crawl and index the images.
Because Google search just looks at the web pages themselves. Things like alt text, any captions, headings on the page–all play into understanding the page a bit better.
And for web search, that’s all Google needs. If all the images were, for example, 404ed all the time or blocked by robots.txt for web search, we would still treat that page exactly the same as if we were able to index all of these images.
This happens at approximately the 24:56 mark in the video.