I changed the IP address of a subdomain, but still doesn't work


If you want blog. URLs to redirect, you need a Redirect Rule. DNS records may point requests to different IP addresses, but they will not by themselves return a 3XX redirect status code to visitor’s browsers, and that may have negative SEO consequences, which are probably the opposite of what you want.

This is probably a result of caching. Purge your browser’s cache, or use incognito mode.