http://en.wikipedia.org/wiki/Denial-of-service_attack
DDoS on IPS and you can configure MPF on the ASA to limit the amount of connections that should reach the server, this would only be if you know the expected amount.
IPS link, please read DDoS information.
http://www.cisco.com/en/US/prod/collateral/vpndevc/ps5729/ps5713/ps4077/data_sheet_c78-459520_ps6120_Products_Data_Sheet.html
Tcp intercept, the ASA is but a mitigation device that will prevent the attack to get to the server but will suffer the consequences like high CPU or running low on resources for other connections that are going through.
http://www.cisco.com/en/US/docs/security/asa/asa82/configuration/guide/conns_connlimits.html
Attacks such like these are normally caused from the Internal LAN but if in any case it is external, developing a contingency plan with your ISP would be best, they can track down the source as you only have access to local resources and black hole them, block the source or get in touch with other providers to track down or attack the source to kill its resources.
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