NAT

Three Switch Function at Layer 2

Address learning: L2 switches & bridges remembers the source hardware address of each frame received on an interface & they enter this information into MAC address table.

Forward/filter decision: When frame is received on an interface, the switch looks at destination hardware address & find exit interface in the MAC table. The frame is only forwarded out the specified destination port.

Loop avoidance: If multiple connections between switches are created for redundancy, network loop can occur, then STP is used.

SFP

The small form-factor pluggable (SFP) or Mini-GBIC is a compact, hot-pluggable transceiver used for both telecommunication and data communications applications. It interfaces a network device mother board (for a switch, router, media converter or similar device) to a fiber optic or copper networking cable. It is a popular industry format jointly developed and supported by many network component vendors.^[1] SFP transceivers are designed to support SONET, Gigabit Ethernet, Fibre Channel, and other communications standards.

Quote

“Competition in [worldly] increase diverts you, until you visit the graveyards,” (Qur’an 102:1-2).

CISCO IOS VERSIONS

AES Encryption

http://www.cs.bc.edu/~straubin/cs381-05/blockciphers/rijndael_ingles2004.swf

DNS