75 Linux · Networking questions from the System Administration bank, written for Indian campus drives and tech interviews. Every question has a verified answer and an AI-tutor explanation on placd.
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A.list listening TCP/UDP ports with their owning process PIDs
B.capture and inspect network packets on an interface
C.show or change NIC settings like speed and duplex
D.show the network hops to a destination
Answer + AI explanation with Pro
2. Which command will list listening TCP/UDP ports with their owning process PIDs?
Junior
A.traceroute host
B.ping -c 4 host
C.ss -tulpn
D.ip -s link
Answer + AI explanation with Pro
3. Which statement is correct?
Junior
A.ss -tulpn — show interface statistics including dropped packets
B.ss -tulpn — fetch only the HTTP response headers from a URL
C.ss -tulpn — persistently open HTTPS in firewalld (apply after --reload)
D.ss -tulpn — list listening TCP/UDP ports with their owning process PIDs
Answer + AI explanation with Pro
4. What does ip addr do?
Junior
A.show the network hops to a destination
B.capture and inspect network packets on an interface
C.show network interfaces and their IP addresses
D.apply firewalld's permanent config without dropping connections
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5. Which command will show network interfaces and their IP addresses?
Junior
A.dig
B.ip addr
C.curl -I url
D.ss -tulpn
Answer + AI explanation with Pro
6. Which statement is correct?
Junior
A.ip addr — show network interfaces and their IP addresses
B.ip addr — list NetworkManager connection profiles
C.ip addr — send 4 ICMP echo requests to test reachability
D.ip addr — resolve a hostname to its IP using DNS
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7. What does ip route do?
Junior
A.show the active rules of the default firewalld zone
B.show the kernel routing table
C.activate a NetworkManager connection profile
D.show or change NIC settings like speed and duplex
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8. Which command will show the kernel routing table?
Junior
A.host example.com
B.dig
C.ss -tulpn
D.ip route
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9. Which statement is correct?
Junior
A.ip route — fetch only the HTTP response headers from a URL
B.ip route — show the kernel routing table
C.ip route — activate a NetworkManager connection profile
D.ip route — show interface statistics including dropped packets
Answer + AI explanation with Pro
10. What does ip link set eth0 up do?
Junior
A.show the kernel routing table
B.resolve a hostname to its IP using DNS
C.show or change NIC settings like speed and duplex
D.bring the network interface eth0 up
Answer + AI explanation with Pro
11. Which command will bring the network interface eth0 up?
Junior
A.tcpdump
B.ip link set eth0 up
C.firewall-cmd --reload
D.curl -I url
Answer + AI explanation with Pro
12. Which statement is correct?
Junior
A.ip link set eth0 up — bring the network interface eth0 up
B.ip link set eth0 up — capture and inspect network packets on an interface
C.ip link set eth0 up — list listening TCP/UDP ports with their owning process PIDs
D.ip link set eth0 up — show or change NIC settings like speed and duplex
Answer + AI explanation with Pro
13. What does nmcli con show do?
Mid
A.query DNS records from the command line
B.show the kernel routing table
C.list NetworkManager connection profiles
D.show network interfaces and their IP addresses
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14. Which command will list NetworkManager connection profiles?
Mid
A.ip link set eth0 up
B.nmcli con show
C.ip -s link
D.firewall-cmd --reload
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15. Which statement is correct?
Mid
A.nmcli con show — capture and inspect network packets on an interface
B.nmcli con show — apply firewalld's permanent config without dropping connections
C.nmcli con show — list NetworkManager connection profiles
D.nmcli con show — persistently open HTTPS in firewalld (apply after --reload)
Answer + AI explanation with Pro
16. What does firewall-cmd --permanent --add-service=https do?
Mid
A.persistently open HTTPS in firewalld (apply after --reload)
B.show network interfaces and their IP addresses
C.list NetworkManager connection profiles
D.show interface statistics including dropped packets
Answer + AI explanation with Pro
17. Which command will persistently open HTTPS in firewalld (apply after --reload)?
Mid
A.ethtool eth0
B.curl -I url
C.firewall-cmd --permanent --add-service=https
D.nmcli con up <name>
Answer + AI explanation with Pro
18. Which statement is correct?
Mid
A.firewall-cmd --permanent --add-service=https — resolve a hostname to its IP using DNS
B.firewall-cmd --permanent --add-service=https — persistently open HTTPS in firewalld (apply after --reload)
C.firewall-cmd --permanent --add-service=https — list NetworkManager connection profiles
D.firewall-cmd --permanent --add-service=https — activate a NetworkManager connection profile
Answer + AI explanation with Pro
19. What does firewall-cmd --reload do?
Mid
A.query DNS records from the command line
B.apply firewalld's permanent config without dropping connections
C.show the network hops to a destination
D.show network interfaces and their IP addresses
Answer + AI explanation with Pro
20. Which command will apply firewalld's permanent config without dropping connections?
Mid
A.ping -c 4 host
B.firewall-cmd --reload
C.curl -I url
D.ip addr
Answer + AI explanation with Pro
21. Which statement is correct?
Mid
A.firewall-cmd --reload — send 4 ICMP echo requests to test reachability
B.firewall-cmd --reload — apply firewalld's permanent config without dropping connections
C.firewall-cmd --reload — list listening TCP/UDP ports with their owning process PIDs
D.firewall-cmd --reload — resolve a hostname to its IP using DNS
Answer + AI explanation with Pro
22. What does dig do?
Junior
A.persistently open HTTPS in firewalld (apply after --reload)
B.show the kernel routing table
C.query DNS records from the command line
D.show the active rules of the default firewalld zone
Answer + AI explanation with Pro
23. Which command will query DNS records from the command line?
Junior
A.dig
B.firewall-cmd --permanent --add-service=https
C.firewall-cmd --reload
D.ping -c 4 host
Answer + AI explanation with Pro
24. Which statement is correct?
Junior
A.dig — show network interfaces and their IP addresses
B.dig — persistently open HTTPS in firewalld (apply after --reload)
C.dig — show the kernel routing table
D.dig — query DNS records from the command line
Answer + AI explanation with Pro
25. What does tcpdump do?
Mid
A.show or change NIC settings like speed and duplex
B.capture and inspect network packets on an interface
C.resolve a hostname to its IP using DNS
D.persistently open HTTPS in firewalld (apply after --reload)
Answer + AI explanation with Pro
26. Which command will capture and inspect network packets on an interface?
Mid
A.ip addr
B.tcpdump
C.curl -I url
D.ip link set eth0 up
Answer + AI explanation with Pro
27. Which statement is correct?
Mid
A.tcpdump — show interface statistics including dropped packets
B.tcpdump — show the active rules of the default firewalld zone
C.tcpdump — show network interfaces and their IP addresses
D.tcpdump — capture and inspect network packets on an interface
Answer + AI explanation with Pro
28. What is /etc/resolv.conf?
Junior
A.a kernel check (rp_filter) that drops packets arriving on the wrong interface
B.the file listing the DNS nameservers the system uses
C.dropped connections when the netfilter connection-tracking table fills
D.serving different DNS answers to internal vs external clients
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29. Which term means: "the file listing the DNS nameservers the system uses"?
Junior
A.firewalld default zone
B./etc/resolv.conf
C.split-horizon DNS
D.NIC bonding mode 4
Answer + AI explanation with Pro
30. Which statement is correct?
Junior
A./etc/resolv.conf — the file mapping static hostnames to IP addresses, checked before DNS
B./etc/resolv.conf — 802.3ad LACP link aggregation for bandwidth and failover
C./etc/resolv.conf — dropped connections when the netfilter connection-tracking table fills
D./etc/resolv.conf — the file listing the DNS nameservers the system uses
Answer + AI explanation with Pro
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