A godaddy hosting plan offers to host 100 website on a single/shared IP. so from the SEO perspective does it good to host all these 100 websites on SINGLE IP? Because in the Google's eye, if all these websites are hosted on single IP... only one domain will have good domain authority; the rest 99 websites DA would not improve; or will not have any effect on DA trying to find this information to kill my confusion
No this is not right information. At single IP your all websites can have good DA if websites have good informative contents and following search engines guidelines. And BTW DA is not Google metrix so no need to worry about it. One IP count in backlinking process means if all 100 websites are linking to any website then these links can consider as single backlink.
The IP is not the issue. But I gave up shared accounts, because the additional websites will also be accessible to the web via a subdomain on the main domain. The secondary sites will be in a subdomain of the main site. I had my own websites competing with each other.
Having multiple websites sharing the same IP address can have negative effects on search engine optimization (SEO) in some cases.
A single IP address hosting several domains can have both beneficial and detrimental effects on SEO. On the plus side, it can reduce hosting costs and consolidate the value and authority of backlinks between the domains. The prospect of shared reputation, whereby one domain's illegal conduct could have an effect on the rankings of other domains on the same IP, as well as resource sharing, where one domain's higher traffic or resource usage could have an impact on the functionality of others, are challenges.