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GK One-Line Question & Answer

15541+ short questions with short answers, covering every category and sub-category on the site — no long articles to scroll through. Good for a fast recap before an exam, or a few minutes of daily practice.

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Computer Networks → Data Link Layer 1

RARP maps MAC address to
IP address
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Computer Networks → Subnetting 5

Class A subnet mask is
255.0.0.0
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Class B subnet mask is
255.255.0.0
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Class C subnet mask is
255.255.255.0
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Subnet mask /24 means
24 bits for network prefix
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Subnet mask for /20 is
255.255.240.0
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Computer Networks → Introduction to Computer Networks 23

Loopback IP address is
127.0.0.1
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CIDR stands for
Classless Inter-Domain Routing
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TTL field in IP header prevents
Packets circulating forever
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MF bit in IP header means
More Fragments
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Path vector routing is used by
BGP
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RIP maximum hop count is
15
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Count to infinity problem occurs in
Distance Vector routing
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Flooding sends packets on
Every outgoing line except incoming
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BGP stands for
Border Gateway Protocol
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Autonomous System is
Group of networks under single administration
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Intra-domain routing is called
Intra-AS or IGP routing
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Split horizon prevents
Routing loops in distance vector by not advertising route back on incoming interface
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Route poisoning advertises failed route with metric
Infinity (16 in RIP)
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Hierarchical routing reduces
Routing table size for large networks
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Default route in routing table matches
Least specific route 0.0.0.0/0
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Longest prefix match selects
Most specific matching prefix
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RIP administrative distance in Cisco is
120
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eBGP administrative distance in Cisco is
20
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Directly connected route administrative distance is
0
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How many usable hosts in /29 network
6
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How many usable hosts in /28 network
14
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How many usable hosts in /27 network
30
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How many usable hosts in /30 network
2
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Computer Networks → Network Layer 5

NAT stands for
Network Address Translation
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DF bit in IPv4 header stands for
Dont Fragment
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IPv4 fragment offset is in units of
8-byte blocks
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Minimum IPv4 header size is
20 bytes
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IHL field in IPv4 measures header length in units of
4-byte words
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Computer Networks → Application Layer 1

DHCP assigns
IP address subnet mask gateway and DNS dynamically
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Computer Networks → Routing Algorithms 5

Distance vector routing algorithm is used by
RIP
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Link state routing algorithm is used by
OSPF
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OSPF stands for
Open Shortest Path First
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OSPF uses which algorithm internally
Dijkstra SPF
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OSPF administrative distance in Cisco is
110
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