From an employer's perspective, certifications are used to weed out applicants, qualify for vendor discounts, establish knowledge baselines, and meet customer contract requirements. Knowing all of this, you can possibly use this to leverage your way to a job and/or higher salary. If a company is looking for a certain certified employee, it is mostly likely going to be because of one the reasons mentioned above. That is it. No hiring manager is going to be impressed with your certification in and of itself. It is just a checklist item. How it affects your chance of being hired or your salary depends on their ease or difficulty in finding applicants with that certification, or their desire for a particular skill set. Experience really super cedes all. Interviewers spend far more time going over your experiences than what certifications you have. Think of certs in a similar vain as a degree.
As far as interviewing, being able to speak the language of the profession impresses far more than what test you took. If you are also able to convey that you've seen it and done it before, then the job is in the bag. Use certs as a springboard to enhance your experience or knowledge. At the end of the day customers/employers just want you to hold their hand and let them know everything is going to be okay.
Now, if you're trying to get your first job than my advice would be to try to relate whatever knowledge or work/life experience you have to that job (visit forums/speak to people in the profession). Show that it won't take a year and forever for you to get up to speed. It may not be what you want to hear, but that's just how it is.
A lot times it's the "little things" that impresses employers. Talk about SLAs, device info (cost/bugs/upgrades/common difficulties), environments (data center, enterprise, service provider, etc), common troubleshooting techniques, industry trends, etc. Being able to effortlessly discuss the "little things" IMO is what really gives experienced workers an edge. Your mouthpiece is your biggest asset. It's the real moneymaker. Everything else is mostly fuel.