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Computer Networks → Introduction to Computer Networks 29

Hamming distance between 11001 and 10110 is
3
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To detect d-bit errors minimum Hamming distance needed is
d+1
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To correct d-bit errors minimum Hamming distance needed is
2d+1
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CRC-32 adds how many redundancy bits
32
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Two-dimensional parity calculates parity for
Both rows and columns
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PPP stands for
Point-to-Point Protocol
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LLC sub-layer provides
Logical Link Control and multiplexing
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MAC sub-layer controls access to
Physical medium
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IEEE 802.3 standard is for
Wired Ethernet
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CSMA/CD is used in
Standard Ethernet
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CSMA/CA is used in
Wireless LAN
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Pure ALOHA maximum efficiency is
36.8%
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Slotted ALOHA maximum efficiency is
36.8%
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In CSMA/CD after collision stations send
Jam signal
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Binary exponential backoff limits maximum wait to
1024 slot times
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1-persistent CSMA transmits with probability 1 when channel is
Free
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In non-persistent CSMA if channel busy station
Waits random time then retries
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Learning bridge builds its table by observing
Source addresses of incoming frames
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Spanning Tree Protocol prevents
Layer 2 loops and broadcast storms
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Root bridge in STP is selected based on
Lowest Bridge ID (priority + MAC)
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BPDU stands for
Bridge Protocol Data Unit
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RSTP convergence is how much faster than STP
Seconds vs 30-50 seconds
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PortFast immediately puts port into
Forwarding state
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BPDU Guard shuts port when
BPDU received on PortFast port
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A transparent bridge is called transparent because
Stations are unaware of its presence
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Switch creates separate collision domain per
Port
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Which layer is responsible for logical addressing
Network
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IP stands for
Internet Protocol
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ARP maps IP address to
MAC address
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Computer Networks → Data Link Layer 7

HDLC flag byte value is
0x7E
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Bit stuffing in HDLC inserts 0 after how many consecutive 1s
5
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Ethernet frame minimum size is
64 bytes
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Ethernet frame maximum size is
1518 bytes
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The preamble in Ethernet frame is
7 bytes
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After 16 collisions in Ethernet the frame is
Discarded and error reported
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Slot time in standard 10 Mbps Ethernet is
51.2 us
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Computer Networks → Wireless Networks 1

IEEE 802.11 standard is for
Wireless LAN
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Computer Networks → OSI Reference Model 1

Hub operates at OSI layer
1
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Computer Networks → IP Addressing 2

IPv4 address is how many bits
32
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IPv6 address is how many bits
128
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