written exam, the candidate has eighteen months to take the lab exam. The candidate has three years after passing the written exam to successfully complete the lab. The lab is an eight-hour, hands-on exam designed to demonstrate that the candidate knows Internetworking theory and demonstrates advanced hands-on mastery. Candidates that do not pass the CCIE lab in that interval must re-pass the written exam before again attempting the CCIE lab exam. The minimum waiting time between attempts is one month. As of July 2014, the CCIE Lab costs $1600 per attempt and ten Cisco locations offer it worldwide. Some of these locations do not offer all CCIE tracks. According to a Cisco survey, $9050 represents the average cost to prepare for CCIE certification as of April 2006, which gets spent mostly on practice equipment and study material. No formal prerequisites currently exist for the CCIE written exam, but Cisco recommends at least 3–5 years networking experience. CCIE exists as the first Cisco Certified qualification and no other Certifications have existed previously. The associate and professional Certifications recognized the fact that CCIE is overkill for many networking personnel. Cisco has chosen not to make lower level Certifications prerequisites for the CCIE certification. One may have the knowledge to hold multiple CCIE Certifications. Adam McCombs cited this qualification as "essentially a PhD in the internet" in Season 1 Episode 10 of Shark Tank. Upon successful completion of the lab exam, Cisco awards a CCIE number to a new CCIE. The first CCIE number allocated (in 1993) started at 1,024 and increased thereafter. As of August 2011, the highest CCIE number allocated reached just over 30,000. The first number they allocated to the first CCIE lab location, rather than to an individual, and featured as a plaque at the entrance to the lab. They awarded Number 1025 to Stuart Biggs, who created the first written exam and first lab exam. The first person to pass both CCIE written and lab exams, known as Terry Slattery, consulted at Cisco when the lab began development. Slattery held the first CCIE who did not work for Cisco. Each CCIE retains their number regardless of how many Certifications he or she receives. Every two years a CCIE has to take a written test to retain the certification. If not done, the certification becomes suspended. After one further year without passing, the certification becomes revoked. One can then