ccna question pdf

ccna question pdf.3.3 Ethernet connectionsA NIC, often referred to as a LAN adapter, connects a computer or network device to a Layer 2 wired or wireless LAN medium. The NIC contains the following components: interrupt request lines (IRQs), memory input/output (I/O) addresses, drivers (software that interacts with the NIC), and MAC addresses.The MAC addresses are solidified into the read-only memory (ROM) of the NIC and are often referred to as solidified addresses (BIAs). However, the MAC address is copied into RAM for use by the driver. Some drivers allow the user to modify the MAC address copied into RAM (the BIA is solidified into ROM and cannot be modified).3.3.1 Cable TypesLANs typically use copper or fiber optic cables. Copper cables may contain only one copper wire for transmitting voltage, or they may contain multiple copper wires. Fiber optic cables use light emitting diodes and lasers to transmit data; in this type of transmission, light is used to represent the binary values 1 and 0: with light for 1, without light for 0.1. Unshielded twisted pair cable is cheaper than fiber optic cable. The Ethernet standard defines Category 3 copper cables.. Coarse cable: uses coarse coaxial cable (no longer used in today's networks) .. Fine cable: using fine coaxial cable (no longer used in today's networks) o . Unshielded twisted pair (UTP): uses 4 pairs of wires where each pair is twisted together. Of these 3 types of copper cables, only UTP is currently used, mainly because it is less expensive than the other two types and is easier to install and troubleshootEasier. While copper cables have their advantages, copper cables including UTP suffer from two disadvantages as follows.. . inability to withstand electromagnetic interference (EMI) and radio frequency interference (RFI); . Cable length is limited. the copper wire inside the UTP is 22 or 24AWG in diameter O UTP for Ethernet has an impedance of 100 ohms and therefore cannot be used with other UTP,such as common telephone lines. Each wire within the copper cable is colored: some are solid and some are fancy. Two pairs of wires carry the active voltage, usually called tip (Tl.T4), and the other four wires carry the inverted voltage, usually called ring (R1-R4) Currently, people usually refer to these