Asymptotes. Calculus.

I came across a question in a book asking for the asymptotes of $y=\sqrt{1+{x}^{2}}$. The answer says it as 2, but I am pretty convinced that there is no asymptote. I somehow think the book is wrong. Any help would be much appreciated.

I came across a question in a book asking for the asymptotes of $y=\sqrt{1+{x}^{2}}$. The answer says it as 2, but I am pretty convinced that there is no asymptote. I somehow think the book is wrong. Any help would be much appreciated.