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Networking Flashcards

7 cards from real Linux practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 Networking flashcards as text

  1. Which command queries a DNS server for information about a domain?

    Answer: dig

    `dig` (Domain Information Groper) queries DNS servers and displays detailed DNS records and responses.

  2. What does the `iptables -L` command do?

    Answer: Lists all current firewall rules

    `iptables -L` lists all rules in all chains of the filter table, showing the current firewall policy.

  3. Which file configures systemd-networkd or NetworkManager for a network interface on modern systems?

    Answer: /etc/network/interfaces on Debian or /etc/sysconfig/network-scripts/ on RHEL

    Interface configuration lives in `/etc/network/interfaces` on Debian-based systems or `/etc/sysconfig/network-scripts/` on RHEL-based systems.

  4. What does setting `net.ipv4.ip_forward=1` in `/etc/sysctl.conf` enable?

    Answer: IP packet forwarding between interfaces, enabling routing

    Enabling `ip_forward` allows the Linux kernel to forward packets between network interfaces, making the host act as a router.

  5. Which protocol does DHCP use at the transport layer?

    Answer: UDP

    DHCP uses UDP (ports 67 for server, 68 for client) because clients need to broadcast before they have an IP address.

  6. What does the `mtr` command combine?

    Answer: ping and traceroute functionality

    `mtr` (Matt's Traceroute) combines continuous ping and traceroute into a real-time, interactive network diagnostic tool.

  7. What is the purpose of the `tc` command in Linux?

    Answer: Traffic control — shaping and scheduling network traffic

    `tc` (traffic control) configures Linux's built-in QoS features, allowing bandwidth limiting, traffic shaping, and packet scheduling.