Senior technical experts can be in short supply, especially if your organization has lots of projects underway. New employees and novices may not know where to turn or may be reluctant to bother or look stupid in front of an expert. One way to cope with a shortage of experts is to appeal to the members of your network for help.
Technical communities of practice can be a wonderful alternative, but not always. When is it safe to use a community of practice or technical network to help with a problem or answer a question?