The Junos OS blocks an HTTP request due to the category of the URL.Which form of Web filtering is being used?（）

A. whitelists, blacklists, SurfControl categories
B. blacklists, whitelists, SurfControl categories
C. SurfControl categories, whitelists, blacklists
D. SurfControl categories, blacklists, whitelists

A. a telnet to port 80
B. a TCP packet with the SYN and ACK flags set
C. an SNMP getnext request
D. an ICMP packet larger than 1024 bytes

A. It prevents the HTTP client or server from timing-out during an antivirus update
B. It prevents the HTTP client or server from timing-out during antivirus scanning.
C. It is an attack.
D. It is used to bypass antivirus scanners.