URL with and without capital letters are there any differences for SERP? some I use big capital some no capital my-site.com/Travel/ My-Site.com/travel/ my-site.com/TRAVEL/ my-site.com/travel/ will these affect google SERP? or which one is better?
Google is insensitive to case when it comes to keywords, so using upper or lower case in a URL won't matter in that regard. However, Google is sensitive to case when it comes to distinguishing between URLs, so be sure to pick one method and stick to it or you can have duplicate content problems.
Domain name doesn't matter, a link to Domain.com is the same as domain.com However, actual URL's are case sensitive. domain.com/File.html and domain.com/file.html Are different URLs, and can have different Pageranks. So it's a good idea to always use lower case when constructing your URL's.