Recent discussions on increasing the efficiency of the Internet's infrastructure have centered on removing the shared Domain Name System (DNS) resolver and using a local resolver instead. In terms of the cache mechanism, this would involve removing the shared cache from the Internet. Although the removal of unnecessary parts tends to simplify the overall system, such a large configuration change would need to be analyzed before their actual removal. This paper presents our analysis on the effect of a shared DNS resolver based on campus network traffic. We found that (1) this removal can be expected to amplify the DNS traffic to the Internet by about 3.9 times, (2) the amplification ratio of the root DNS is much higher (about 6.3 times), and (3) removing all caching systems from the Internet is likely to amplify the DNS traffic by approximately 16.0 times. Thus, the removal of the shared DNS resolver is not a good idea. Our data analysis also revealed that (4) many clients without local caches generate queries repeatedly at short intervals and (5) deploying local caches is an attractive technique for easing DNS overhead because the amount of traffic from such clients is not small.