You may run a profitable, fast-growing startup, but without an active network of trusted and influential connections, your business probably isn't living up to its full potential in terms of sales, profits, and growth.

Referrals and connections are the currency of the business world, and taking the time to build and nurture your network really pays off in the form of new leads, personal opportunities, and good old-fashioned social capital.

Even if you have 500+ connections on LinkedIn and a Klout score that's through the roof, there's really no way to know how strong your network is without actually testing it.

Here are three ways to assess your network and ensure your connections are happy and healthy:

1. Perform a network audit. To check that your network is thriving, set aside some time each month or quarter to ask yourself several key questions about the state of your community interactions and relationships:

  • Who's in your circle? Ideally, you should aim to build a diverse network of professionals across a variety of industries (rather than scores of colleagues from your core industry or the same firm). Check out how well-rounded your network is, and if it seems too one-sided, it might be time to reach out to new colleagues in other industries.
  • How often are you interacting with others? The frequency of interactions with your network can give you an idea of how well it's functioning. If you never seem to receive any queries, recommendations, or invitations, try squeezing in another social event this month, or spend an extra hour making new connections and offering endorsements on LinkedIn.
  • Are you able to call on your network? A healthy, active network will be there for you whenever you need it--not just in times of trouble. Try reaching out, and if nobody responds, you might need to dedicate more time to cultivating those relationships more actively (and with reciprocity) at conferences and industry events.

2. Create a keep-in-touch system. For every group and community you're a part of, you should have an efficient system for keeping in touch with those connections. Whether it's sending a monthly newsletter, staying active on LinkedIn, or setting up regular in-person coffee or lunch dates to share ideas, staying in front of your network will keep you top of mind and help generate leads, referrals, and new business opportunities.

3. Pay it forward. A network can only thrive if its members actively participate and create opportunities for one another. You don't have to wait for others to come to you with questions and referrals. Take the initiative to reach out first, and offer something of value.

Paying it forward can take many forms. You could engage in more speaking opportunities, agree to help at an associate's event, hand out business cards with personalized notes, refer others for opportunities you hear about, and just keep particular members of your network in the back of your mind as you go about your business. Proactively offer referrals or testimonials; people will love you for doing that (and be more inclined to reciprocate).

It's a good idea to perform this network checkup regularly. Being aware of your network's health will allow you to recognize when your connections are growing stale and be more proactive about reaching out to strengthen those relationships.

Remember: The best way to build solid connections is to earn a reputation of being a person who adds value for others in virtually every interaction you have with them. When you take it upon yourself to diversify your network, stay in touch, and look for ways to help those around you, they'll repay you over time with their support, referrals, connections, introductions, and influence.