It depends on what that jr engineer is going to be doing. If it were me, I would think the jr engineer woul have a CCNA. Having more experience is always a plus. Currently, my jr engineer is a CCENT but has some experience and a deadline to finish his CCNA by a specific date. Personally, I wouldn't require a CCDA for a jr position. Now, if he wated to advance to a engineer or sr engineer, I could see it.
"It depends", as Jared said. Really depends on both the company and the specific position for which you apply. It many cases a junior engineer would be fine with something akin to a CCENT or some CCNA-level knowledge. As long as you have some basic knowledge about how networks operate. Most hiring managers understand that a person applying for a junior position will have little to no job experience. However the more experience that you can show, whether job, volunteer, or personal lab work at home, will be better. It shows you are committed to furthering your knowledge and have actually worked with the concepts.
Don't get too caught up on experience and certifications, and focus your efforts on understanding the concepts and increasing your strength in knowledge. Once you land that first job you'll begin to see approximate experience and knowledge levels of your peers. Understand, though, that it can vary greatly between companies. At some places, a "Senior Engineer" is simply someone who has a specific number of years of experience and hasn't committed any major blunders. A Senior Engineer at another company may command CCNP/CCIE level knowledge, the ability to manage others, and some business experience. It can vary greatly based on company and position.
I cannot over-stress the value of observation while you are on the job. I have met engineers who have not obtained Senior Engineer status because they lack one course in obtaining their BS degree. However, they certainly held and practiced senior knowledge daily. In other cases, I've met senior engineers that did not fully grasp the concept of VLANs or did not know the difference between bridging and port aggregation.
Focus on your knowledge, apply for those jobs, and show them what you know. Don't get caught up about having certain certifications, but continue your journey and obtain the certs as you go as a measure of your progress. Good luck!
Good points and observations about how different organizations may do things. I have seen one company organize their position level to the Cisco certification levels. A jr engineer CCNA, a engineer was CCNP and the seniors were CCIE. It was an interesting approach. Not one that I would totally agree with, but interesting none the less.
Seniority as far as time is another factor. One that I Reay done agree with either. I see time with the organization as a tie breaker. I would first go for the more knowledgable, experienced, innovative, observant candidate. If 2 candidates were pretty much equal in those areas, then I would use tenure as a tie breaker.