A new network administrator is hired to replace a consultant that has been keeping the network running for several months. After a month, the network administrator is having network issues. The problems are easily resolved and appear to be changes in the server settings. The log files on the servers do not contain any error or messages related to the issues. Which of the following is a possible cause of the issues?
A. TACAS\Radius misconfiguration is causing logs to be erased
B. ICMP ping of death is resetting DHCP and DNS on the server
C. A backdoor has been installed to access the network
D. The last ACL on the router is set to Deny All