Rdsrv dot com Browser Hijacker on Mac
Rdsrv dot com is the domain name associated with a browser hijacker that can affect any browser on your Mac, including Safari, Chrome and Firefox.
Browser hijackers are a type of potentially unwanted application that can install on your Mac quietly, without asking for your explicit consent as a user. Browser hijackers will usually display some sort of intrusive behavior such as displaying unwanted pop-up ads or advertising injected and embedded inside web pages, and can also collect data about user browsing habits and other potentially personally identifiable information.
If you keep seeing advertising pop-ups as you browse and those ads originate from Rdsrv dot com, you most likely have the Rdsrv browser hijacker on your Mac. The ads can also manifest as embedded content you normally don't see in your search results pages for example.
Hijackers similar to Rdsrv dot com can also potentially display links and ads leading to malicious pages and help further infections with more dangerous, full-blown malware.
The most common way for similar potentially unwanted applications to enter your Mac is through app bundle installers. Those are packages containing multiple apps, usually distributed through free download websites of less than stellar reputation.
A bundler will commonly contain a legitimate application, with one or more potentially unwanted apps piggy-backing inside the same installer. The bundle installers are notorious for the poor disclosure of their contents and a lot of the time, those PUAs will install on your Mac without you ever realizing they were in the bundler in the first place.
The most reliable way to steer clear of similar bundles is to only source your applications from reliable, properly curated sources such as the official App Store.