Regex to find keywords in URL

I am trying to write a Regex to detect specific keywords in a URL. For example I am looking for the word "update" in a URL and it could be as part of the domain or subdomain like these:

myupda开发者_运维知识库te.example.com

www.my-update.com

I tried this but only get subdomains that start with "update":

http\:\/\/\bupdate\b

Any help would be appreciated!

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/http:\/\/[^\/]*update/