350-018v4 Free Dumps Study Materials
Question 8: Which statement is true about SYN cookies?
A. The state is kept on the server machine TCP stack.
B. A system has to check every incoming ACK against state tables.
C. SYN cookies do not help to protect against SYM flood attacks.
D. No state is kept on the server machine state but is embedded in the initial sequence number.
Correct Answer: D
http://www.cisco.com/c/en/us/td/docs/ios-xml/ios/sec_data_zbf/configuration/xe-3s/sec-data-zbf-
xe-book/conf-fw-tcp-syn-cookie.html
The Firewall TCP SYN Cookie feature helps prevent SYN-flooding attacks by intercepting and
validating TCP connection
requests. The firewall intercepts TCP SYN packets that are sent from clients to servers. When the TCP
SYN cookie is
triggered, it acts on all SYN packets that are destined to the configured VPN Routing and Forwarding
(VRF) or zone.
The TCP SYN cookie establishes a connection with the client on behalf of the destination server and
another
connection with the server on behalf of the client and knits together the two half-connections
transparently. Thus,
connection attempts from unreachable hosts will never reach the server. The TCP SYN cookie
intercepts and forwards
packets throughout the duration of the connection.