for detecting DOS attacks (DDOS)

show ip cache
show ip cache fastEthernet 0/0.311 flow

Compress the running config then write it to the startup memory

configure
service compress-config
write mem

Setup a default route. The following routes all traffic to 192.168.1.1

R2(config)#ip route 0.0.0.0 0.0.0.0 192.168.1.1