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I try to use a CDN where possible to allow for faster delivery. one example of a CDN which is great for responsive imagery is Cloudinary, this is due to the dynamic way in which you can serve scaled images. Lazy load is also a benefit simply due to connection speeds etc and loading behind the scenes.

Hello Micey123, That sounds good except you should put the sitemap reference for xyz.abcd.com within that subdomain's robots.txt file as well: xyz.abcd.com/robots.txt, as each subdomain should have its own robots.txt file.

Hi Bridget thanks for share

Hi Micey, Is there some additional info you're still looking for? The resources from Martin look pretty comprehensive to me, so I would second his recommendations. You can also just use Chrome DevTools for emulating different screens as a first step (although you'll always want to do real device testing as well).

Thank you, Christy!