Title text:
Please, we need your help. Our research suggests you're the last living descendant of the person who knew how to format this config file.
Transcript:
Transcript will show once it’s been added to explainxkcd.com
Source: https://xkcd.com/3245/
Randall isn't saying that the internet is only 24 (I mean, he's been making xkcd for 20 years and was on it before that). He's saying that his mental conception of the internet is still "new exciting thing," and the fact that it's been around for 24 years means that he's currently being haunted.