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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 Fundamentals → Introduction to Computer 40

OpenFlow protocol is used in?
SDN to communicate between controller and forwarding devices
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Network Function Virtualization (NFV) means?
Running network functions (firewall, LB) as software on standard hardware
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Which DNS record type maps hostname to IPv4 address?
A
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Which DNS record maps hostname to IPv6 address?
AAAA
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DNS MX record is used for?
Mail server routing
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DNS CNAME record creates?
Alias from one hostname to another
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Reverse DNS lookup uses which DNS record?
PTR
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DNS SOA record contains?
Start of Authority: primary NS, admin email, serial, refresh, retry, expire
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DNS TTL (Time To Live) controls?
How long DNS resolvers cache the record
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DNSSEC adds to DNS?
Cryptographic signatures to prevent DNS spoofing
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DoH (DNS over HTTPS) provides?
Encrypted DNS queries via HTTPS (port 443)
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DoT (DNS over TLS) encrypts DNS using?
TLS on port 853
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DHCP lease time determines?
How long a device keeps its assigned IP before renewal
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DHCP DORA process stands for?
Discover, Offer, Request, Acknowledge
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APIPA address is assigned when?
DHCP server is unavailable — self-assigned fallback address
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Which protocol is used for dynamic routing in ISP backbone networks?
BGP
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Spanning Tree Protocol (STP) prevents?
Layer 2 switching loops
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RSTP (802.1w) improves on STP by?
Faster convergence (seconds vs minutes)
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Which protocol allows a switch to become a DHCP client?
DHCP client (standard)
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LACP (Link Aggregation Control Protocol) is used for?
Bundling multiple physical links into one logical link
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Port mirroring/SPAN is used for?
Copying traffic from one port to another for analysis
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802.1Q VLAN tagging adds how many bytes to Ethernet frame?
4
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VLAN ID range in 802.1Q is?
1-4094
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QinQ (802.1ad) double tagging is used for?
Service provider VLANs (VLAN tunneling for customer traffic)
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PoE (Power over Ethernet) provides?
DC power over Ethernet cables to devices (IP cameras, APs)
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Which organization assigns globally unique MAC addresses?
IEEE (first 3 bytes = OUI)
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Unicast MAC address has LSB of first byte?
Set to 0
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Broadcast MAC address is?
FF:FF:FF:FF:FF:FF
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Which protocol detects IP address conflicts on a network?
Gratuitous ARP
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ICMP type 0 is?
Echo Reply
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ICMP type 11 (Time Exceeded) is used by?
traceroute
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TCP RST flag is used to?
Abruptly terminate connection
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TCP FIN flag initiates?
Graceful connection close
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TCP sequence numbers provide?
In-order delivery and reliable data reassembly
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TCP sliding window implements?
Flow control — limits sender based on receiver buffer space
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TCP slow start algorithm?
Begins with small congestion window, doubling until threshold
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CUBIC is a?
TCP congestion control algorithm (default in Linux)
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QUIC protocol developed by Google uses?
UDP as transport, providing reliability and security like TCP+TLS
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HTTP/3 is built on?
QUIC (over UDP)
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WebSocket provides?
Full-duplex persistent connection over single TCP connection
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