Salary Survey Extra is a series of periodic dispatches that give added insight into the findings of our most recent Salary Survey. These posts contain previously unpublished Salary Survey data.

Almost everyone uses a computer network at some point during the day, whether it's an enterprise network with more than 1,000 workstations connected, or a simple home wireless network that lets your computer and television team up to deliver your favorite video streaming service.

Most people can conceptualize and implement that home network on their own. The enterprise network, however — like the many much larger networks that connect the world around us — requires a greater degree of expertise. That's the sort of training undertaken by specialists who earn the Cisco Certified Design Professional (CCDP) credential, which showed up at No. 37 on our most recent Salary Survey 75 list.

Cisco's certification program stretches around the globe, and we heard from CCDP-certified individuals both in the United States (where roughly 43 percent of respondents are located) and 15 different countries around the world: Argentina, Australia, Brazil, Canada, Guatemala, Hungary, Malaysia, Mexico, Netherlands, Norway, Saudi Arabia, Singapore, South Africa, the United Kingdom, and Venezuela. It's good to be CCDP-certified in the United States, where credential holders enjoyed an average annual salary of $121,350 in 2016, with a median annual salary of $120,000. Outside the United States, the average annual salary dipped to $90,130, with a median annual salary of $72,500.

Most of the CCDP holders who responded to the survey are men (95.7 percent), though we did have a small number of women in the mix (4.3 percent). It would seem that CCDP certification is a bit of a mid-career milestone, given that we only heard from a smattering of CCDP holders age 34 or younger (12.8 percent of those surveyed) and nobody at all younger than 25. Most of those surveyed are either between the ages of 35 and 44 (the lion's share, at 53.2 percent of respondents) or between the ages of 45 and 54 (23.4 percent), with a handful checking in between the ages of 55 and 64 (10.6 percent).

The highest level of education attained by most CCDP holders is either a bachelor's degree (46.8 percent of those surveyed) or master's degree (27.7 percent), though we did hear from an unusually large group (10.6 percent) who have professional degrees (such as a juris doctor). Most of the rest of those we heard from either completed their formal education with an associate's (two-year) degree (6.4 percent) or finished some level of technical training without going to college (4.3 percent).

Employment among CCDP holders is excellent, with 97.9 percent of respondents employed full-time. The remaining 2.1 percent are part-time employees, meaning that we didn't hear from a single CCDP-certified individual who is out of work. Among those who have jobs, most are doing at least a bit of extra work: More than half of those surveyed either work between 41 and 50 hours per week (40.4 percent) or put in more than 50 hours (13.2 percent). About a third of respondents (29.8 percent) have a standard 40-hours work week, while a fortunate 14.5 percent work between 31 and 39 hours per week, and 2.1 percent have a schedule that comes in between 20 and 30 hours per week.

As many IT certifications do, CCDP leans heavily toward the "senior specialist" tier of the workplace org chart, which claims 54 percent of those surveyed. Other CCDP holders are primarily either rank-and-file employees (16.6 percent of respondents) or specialists (8.7 percent). There is a notable chunk of room for CCDP holders at the top of the pyramid, however, with the remaining roughly 20 percent of respondents rating either as managers (6.2 percent of those surveyed), senior managers (4.9 percent), directors (4.3 percent) or executives (5.7 percent).

As noted earlier, CCDP is a credential for people with a high degree of computer networking fluency. An impressive 66 percent of those surveyed have worked in a role that directly utilizes one or more of their certified skills for more than a decade, and a further 25 percent have been so engaged for either between 9 and 10 years (4.3 percent of those surveyed) or between 6 and 8 years (21.2 percent).

Finally, here's the view of CCDP holders on key questions from the survey about how certification impacts job performance:

At my current job I use skills learned or enhanced through certification:
Several times a day: 57.4 percent
Several times a week: 31.9 percent
Several times a month: 8.8 percent
Occasionally: 1.9 percent
Rarely: [No responses]

Since becoming certified, I feel there is greater demand for my skills.
Strongly agree: 36.1 percent
Agree: 51.1 percent
Neither Agree nor Disagree: 8.5 percent
Disagree: 4.3 percent
Strongly Disagree: [No responses]

Becoming certified has increased my problem-solving skills.
Strongly agree: 36.1 percent
Agree: 51.1 percent
Neither Agree nor Disagree: 4.7 percent
Disagree: 4.3 percent
Strongly Disagree: 3.8 percent

Becoming certified has increased my workplace productivity.
Strongly agree: 29.8 percent
Agree: 53.2 percent
Neither Agree nor Disagree: 10.8 percent
Disagree: 1.7 percent
Strongly Disagree: 4.5 percent