Linux+ V8 Network Troubleshooting Quiz

1. When bridging two networks in a hybrid setup, which tool is typically used to create the bridge interface?

Brctl or ip link add type bridge

Vconfig

Iptables

Route

2. A hybrid network experiences intermittent packet loss. Which tcpdump filter would help isolate retransmitted TCP packets?

Tcpdump -i eth0 'tcp[tcpflags] & tcp-ack != 0'

Tcpdump -i eth0 'tcp[tcpflags] & tcp-syn != 0'

Tcpdump -i eth0 'tcp.analysis.retransmission'

Tcpdump -i eth0 'icmp'

3. You need to verify end-to-end TCP connectivity to a remote service on port 443. Which tool provides the most detailed output?

Telnet hostname 443

Nc -zv hostname 443

Curl -v https://hostname

Ping hostname

4. In a hybrid environment with multiple DNS servers, which file or service controls DNS query order on modern Linux systems?

Systemd-resolved or /etc/resolv.conf

/etc/hosts only

Nsswitch.conf alone

Iptables rules

Submit

7. A hybrid cloud application requires consistent IP addressing across migrations. Which approach best supports this?

Use static IP addresses and IPAM

Rely on DHCP with short lease times

Use link-local addresses

Configure floating IPs only

8. To temporarily disable IPv6 on a Linux system without reboot, which sysctl parameter should be set to 1?

Net.ipv6.conf.all.disable_ipv6

Net.ipv4.ipv6_only

Kernel.ipv6_enabled

Net.ipv6.disable_all

Submit

10. A VPN tunnel between on-premises and cloud is dropping packets. MTU fragmentation is suspected. What is the typical MTU for VPN tunnels?

1500 bytes

1460 bytes or less

9000 bytes

576 bytes

11. A server loses network connectivity after a kernel update. Which command should you run first to verify the network interface status?

Ip link show

Route -n

Netstat -an

Arp -a

Submit

13. A virtual machine on a cloud provider cannot resolve hostnames after migration. The resolv.conf is correct. What should you check next?

Cloud security group DNS egress rules

Local resolver cache (systemd-resolved)

DHCP client logs

Kernel routing table

14. You configure ufw rules but traffic is still blocked. Which step did you likely forget?

Enable ufw with 'ufw enable'

Set default policy to ALLOW

Reload the kernel module

Restart the network service

Submit

16. When troubleshooting DHCP on a Linux client, which file contains the IP configuration after successful lease negotiation?

/etc/dhcp/dhclient.conf

/var/lib/dhcp/dhclient.leases

/etc/network/interfaces

/proc/net/route

17. A client cannot reach a cloud-hosted server via SSH, but ping succeeds. What is the most likely issue?

ARP table corruption

Security group or firewall blocking TCP 22

Routing table misconfiguration

DNS cache poisoning

18. You need to verify which process is listening on port 8080. Which command provides the process ID and name?

Lsof -i :8080

Ss -tlnp | grep 8080

Netstat -tln | grep 8080

Both a and b

19. A hybrid environment shows DNS resolution failing for internal hosts but working for external domains. What is the most likely cause?

Firewall blocking port 53 inbound

Incorrect search domain in resolv.conf

Split DNS configuration mismatch

Network interface MTU too low

20. When using nmcli to configure a static IP address on eth0, which option sets the connection to activate automatically at boot?

Autoconnect yes

Auto-start enable

Boot-activate true

Persistent on

Linux+ V8 Network Troubleshooting in Hybrid Environments Quiz

1. When bridging two networks in a hybrid setup, which tool is typically used to create the bridge interface?

2.

What first name or nickname would you like us to use?

2. A hybrid network experiences intermittent packet loss. Which tcpdump filter would help isolate retransmitted TCP packets?

3. You need to verify end-to-end TCP connectivity to a remote service on port 443. Which tool provides the most detailed output?

4. In a hybrid environment with multiple DNS servers, which file or service controls DNS query order on modern Linux systems?

5. A service listening on 127.0.0.1 is unreachable from another host. To make it accessible network-wide, bind it to ____.

6. When troubleshooting netfilter/iptables, enabling connection tracking helps identify ____.

7. A hybrid cloud application requires consistent IP addressing across migrations. Which approach best supports this?

8. To temporarily disable IPv6 on a Linux system without reboot, which sysctl parameter should be set to 1?

9. You see 'UNREACHABLE' in traceroute output. This typically means ____.

10. A VPN tunnel between on-premises and cloud is dropping packets. MTU fragmentation is suspected. What is the typical MTU for VPN tunnels?

11. A server loses network connectivity after a kernel update. Which command should you run first to verify the network interface status?

12. The command 'ip route show' returns no default route. To add a default gateway of 192.168.1.1, use ____.

13. A virtual machine on a cloud provider cannot resolve hostnames after migration. The resolv.conf is correct. What should you check next?

14. You configure ufw rules but traffic is still blocked. Which step did you likely forget?

15. In a hybrid environment, a packet trace shows traffic leaving your interface but not returning. This suggests ____.

16. When troubleshooting DHCP on a Linux client, which file contains the IP configuration after successful lease negotiation?

17. A client cannot reach a cloud-hosted server via SSH, but ping succeeds. What is the most likely issue?

18. You need to verify which process is listening on port 8080. Which command provides the process ID and name?

19. A hybrid environment shows DNS resolution failing for internal hosts but working for external domains. What is the most likely cause?

20. When using nmcli to configure a static IP address on eth0, which option sets the connection to activate automatically at boot?