Linux DNS Troubleshooting Quiz for Network Pros

1. Which tool can be used to perform a reverse DNS lookup on Linux?

Nslookup with -reverse flag

Dig -x IP_address

Host -r IP_address

Both b and c

2. The `resolvectl` command on systemd-based systems is used to check DNS configuration. True or False?

True

False

3. A DNS server logs show REFUSED responses. What is the most likely cause?

Network connectivity issue

Access control list (ACL) restrictions

Incorrect TTL value

DNSSEC validation failure

4. Which command displays the DNS query path and response time for a hostname?

Nslookup hostname

Dig hostname +trace

Host hostname -v

Both a and b

5. What is the purpose of the /etc/hosts file in DNS resolution?

Local hostname-to-IP mapping before DNS query

Stores remote DNS server addresses

Configures DNS caching

Enables DNS logging

6. A DNS zone transfer fails. Which record type is required for zone transfers?

A record

NS record

SOA record

Both b and c

7. Which file contains the list of DNS servers that a Linux client should query?

/etc/hosts

/etc/resolv.conf

/etc/hostname

/etc/network/interfaces

8. The `rndc` tool is used to manage BIND. What does 'rndc reload' accomplish?

Restarts the BIND daemon completely

Reloads zone files without restarting

Clears DNS cache

Enables DNSSEC validation

9. What does the TTL (Time To Live) value control in DNS records?

How long DNS data is cached

Maximum query timeout

Number of DNS servers queried

DNS record priority

10. A DNS server is not responding. Which command tests connectivity to the DNS server?

Ping DNS_server_IP

Nslookup @ DNS_server_IP

Traceroute DNS_server_IP

All of the above

11. Which file stores the primary DNS resolver configuration on most Linux systems?

/etc/resolv.conf

/etc/dns.conf

/etc/network/dns

/etc/named.conf

12. The `systemctl restart named` command fails. Where would you check for configuration syntax errors?

/var/log/syslog

/etc/named.conf

Journalctl output

All of the above

13. What does DNSSEC provide for DNS queries?

Faster query responses

Authentication and integrity of DNS data

Automatic DNS caching

Increased query bandwidth

14. A client cannot resolve a hostname. Which command checks if the local resolver is working?

Ping hostname

Nslookup hostname

Traceroute hostname

Ifconfig

15. What does the `systemctl status named` command do in DNS troubleshooting?

Checks BIND daemon status

Restarts DNS service

Enables DNS logging

Clears DNS records

16. Which configuration file is used by BIND (Berkeley Internet Name Domain) on Linux?

/etc/resolv.conf

/etc/named.conf

/etc/bind.conf

/etc/dns/config

17. What is the default port used by DNS for queries and responses?

25

53

110

143

18. The `dig` command is used to query DNS information. What does the +trace option do?

Traces the DNS query path from root nameserver

Enables debugging mode

Traces network packets

Clears the DNS cache

19. Which DNS record type maps an IP address to a hostname?

A record

CNAME record

PTR record

MX record

20. What does the `nslookup` command primarily do in DNS troubleshooting?

Starts the DNS daemon

Queries DNS servers for name resolution

Modifies DNS cache

Blocks DNS queries

Linux Network Pro Troubleshooting DNS on a Linux Server Quiz

1. Which tool can be used to perform a reverse DNS lookup on Linux?

2.

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

2. The `resolvectl` command on systemd-based systems is used to check DNS configuration. True or False?

3. A DNS server logs show REFUSED responses. What is the most likely cause?

4. Which command displays the DNS query path and response time for a hostname?

5. What is the purpose of the /etc/hosts file in DNS resolution?

6. A DNS zone transfer fails. Which record type is required for zone transfers?

7. Which file contains the list of DNS servers that a Linux client should query?

8. The `rndc` tool is used to manage BIND. What does 'rndc reload' accomplish?

9. What does the TTL (Time To Live) value control in DNS records?

10. A DNS server is not responding. Which command tests connectivity to the DNS server?

11. Which file stores the primary DNS resolver configuration on most Linux systems?

12. The `systemctl restart named` command fails. Where would you check for configuration syntax errors?

13. What does DNSSEC provide for DNS queries?

14. A client cannot resolve a hostname. Which command checks if the local resolver is working?

15. What does the `systemctl status named` command do in DNS troubleshooting?

16. Which configuration file is used by BIND (Berkeley Internet Name Domain) on Linux?

17. What is the default port used by DNS for queries and responses?

18. The `dig` command is used to query DNS information. What does the +trace option do?

19. Which DNS record type maps an IP address to a hostname?

20. What does the `nslookup` command primarily do in DNS troubleshooting?