LPI 102-500 Dumps

 The keywords dns and files can be used in the /etc/nsswitch.conf file to specify a source for host name lookups. The keyword dns means that the system will use the Domain Name System (DNS) to resolve host names to IP addresses. The keyword files means that the system will use the local /etc/hosts file to resolve host names to IP addresses. The order of the keywords on the line determines the order in which the sources will be queried. For example, the following line in /etc/nsswitch.conf:

hosts: files dns

means that the system will first check the /etc/hosts file for a matching host name, and if not found, it will query the DNS servers configured in /etc/resolv.conf. The other keywords in the question are not valid for the hosts database. The keyword resolv is used for the services database, which contains network service names and port numbers. The keyword remote is not a standard keyword, but it may be used by some applications to implement their own name service providers. The keyword hosts is the name of the database itself, not a source for it. References:

• [LPI Linux Administrator - Exam 102 Objectives - Topic 109: Networking Fundamentals]
• nsswitch.conf(5) - Linux manual page
• What is the /etc/nsswitch.conf file in Linux – TecAdmin

The traceroute program can be used to determine the routing path to a given destination by sending packets with incrementing TTL values and recording the source of the ICMP time exceeded messages. This way, it can show the intermediate hops and the round-trip times for each packet. The other programs have different purposes: dig is used to query DNS servers, netstat is used to display network connections and statistics, ping is used to test the reachability of a host by sending ICMP echo requests and measuring the response time, and route is used to manipulate the routing table. References:

• LPI 102-500 Exam Objectives, Topic 110: Network Fundamentals, Weight: 4, 110.3 Basic network troubleshooting
• LPI 102-500 Study Guide, Chapter 10: Network Fundamentals, Section 10.3: Basic Network Troubleshooting, Page 125-126

The tool that reports not only the response from the name server but also details about the query is dig. Dig stands for domain information groper and it is a command-line tool that can query DNS servers for various types of records. Dig can also provide additional information such as the query time, the server address, the query options, and the response code. Dig is a powerful and flexible tool that can be used for DNS troubleshooting and testing123 References:

• 1: How to use the dig command - Linux.com
• 2: dig(1) - Linux manual page - man7.org
• 3: Top 6 Tools for DNS Troubleshooting | Total Uptime®