On August 19^th, an obstacle occurred in Course Registration by students with odd numbers for the Fall semester. The Office of Information and Communication Technology of Chung-Ang University (OICT) analyzed the cause of this incident saying it was due to an influx of external traffic and abnormal access attempts. They suspected it was DDOS attacks. DDOS (Distributed Denial of Service) is an attack paralyzing a service system using zombie PCs.[1] On the registration day for odd numbers, there were more than 130 attempts to attack from foreign IPs compared to the case of the class of even numbers.​​​​​​​ In response, the OICT reported to the Korean National Police Agency Cyber Bureau and the Ministry of Education, Cyber Security Center. OICT also said that they will come up with improvement plans for the course registration system through continuous consultations with university headquarters and security groups, to prevent future DDOS attacks. Chang-Ang University figured it is difficult to progress the registering on the same day if the attack was planned. Thus, the university postponed the registration date for odd numbers from the 19^th to the 24^th. A total of four DDOS attacks occurred in the process of registering for courses on August 24^th. The OICT responded to traffic suspected as attacks in real-time in cooperation with mobile carriers. Therefore, the registration for courses could be completed well.