Subnet Masks: When Jack checks Palmer's computer, the screen shows the subnet mask address identical to his IP address. Subnet mask addresses always start with the digit 255 at the beginning of the four digits (the exception being the subnet mask address 0.0.0.0.). Also subnet masks can only have the following numbers as well as 255 and 0: 192, 224, 240, 248, 252 and 254. Example: 255.255.255.192 would be considered as a real subnet mask.
IP Addresses: When Chloe asks Jack to give her the IP address to Palmer's computer, Jack finds the IP address as; 2220.127.116.11. . IP addresses never go above the number '255' anywhere in the four digit columns.
CTU obtains video surveillance footage that implicates Jack as President Palmer's assassin, but Jack has an airtight alibi: Just before Palmer's death, he was standing in an oil field (under his assumed name), speaking to a supervisor who'd promised him a chance at some work the next day. All Jack had to do was give his alibi, and he would've been exonerated in Palmer's death.