Here's why:

* Eukaryotes have a true nucleus enclosed by a membrane, along with other membrane-bound organelles. Examples include animals, plants, fungi, and protists.

* Prokaryotes lack a true nucleus and other membrane-bound organelles. They have a simpler structure, with their DNA located in a region called the nucleoid. Eubacteria (also known as bacteria) are a type of prokaryote.

Therefore, Eubacteria are not eukaryotic, but instead belong to the prokaryotic domain.