Wu Zhou, an analyst at IDC, said Cisco's CCIE and related certification programs are at the center of the company's highly profitable services division, which last quarter brought in more than $1 billion in revenue with a gross profit of 68%.

Because Cisco has such a highly developed certification program, workers in customers' IT shops have a higher level of insight about fixing Cisco hardware and software than other vendors' gear, Zhou said.

When a system or part breaks, Cisco's customers are more likely to be able to fix the part because of their training, even if they did not pass a CCIE exam, Zhou said. At least they can take the first steps in repair before calling Cisco for help, which reduces Cisco's costs, she said. "Services at Cisco are highly leveraged," she said.

A Cisco spokeswoman described the purpose of the exams more generally, pointing to an online description: "It's a challenge to keep today's networks running efficiently, and CCIE exams require candidates to prove they have the skills needed to meet that challenge. Exams are developed to reflect network operations in the real-world, draw on the experience of experts in a variety of disciplines and evolve along with the industry."