102-500 Exam Results

The parameter that must be passed to ifconfig to activate a previously inactive network interface is up. The up parameter tells the kernel to activate the network interface and allow it to send and receive packets. The opposite of up is down, which deactivates the network interface. The up parameter is part of the topic 109.2: Basic network configuration, which is one of the objectives of the LPI Linux Administrator - 102 exam12. References: 1: 2:

The routing table shows how the kernel will route packets to different destinations based on the destination IP address, the gateway, the netmask, the flags, the metric, and the interface. The kernel will try to find the most specific route that matches the destination IP address, which means the route with the longest netmask. If there are multiple routes with the same netmask, the kernel will use the route with the lowest metric. If there is no matching route, the kernel will use the default route, which is the route with the destination 0.0.0.0.

In this case, the destination IP address is 192.168.2.150, which belongs to the network 192.168.2.0/24. The routing table has a specific route for this network, which is the second entry. The gateway for this route is 0.0.0.0, which means that the packet will be directly transmitted on the interface eth0, without passing through any router. The netmask for this route is 255.255.255.0, which means that the network has 256 possible hosts. The flags for this route are U, which means that the route is up, and G, which means that the route is to a gateway. The metric for this route is 0, which means that it has the highest priority. Therefore, the kernel will use this route to handle the outgoing packet to the destination 192.168.2.150.

References:

How To Display Routing Table In Linux - RootUsers

route command in Linux with Examples - GeeksforGeeks

Understand the basics of Linux routing | TechRepublic

The keyword files must be listed in the hosts option of the Name Service Switch configuration file in order to make host lookups consult the /etc/hosts file. The files service specifies that the local files, such as /etc/hosts, should be used as a source of information. The order of the services on the line determines the order in which those services will be queried, in turn, until a result is found. For example, if the hosts option is set to:

hosts: files dns

then the /etc/hosts file will be searched first, and if no match is found, the DNS server will be queried next. If the hosts option is set to:

hosts: dns files

then the DNS server will be queried first, and if no match is found, the /etc/hosts file will be searched next. 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

nsswitch.conf: Name Service Switch configuration file

To find the number of IP-addresses that can be used for unique hosts inside an IPv4 subnet, we need to calculate the number of bits that are used for the host part of the IP address. The host part is the part that is not used for the network prefix, which is indicated by the slash notation (/) followed by a number. The number after the slash represents the number of bits that are used for the network prefix, out of the total 32 bits of an IPv4 address. The remaining bits are used for the host part. For example, in the subnet 192.168.2.128/28, the number 28 means that the first 28 bits are used for the network prefix, and the last 4 bits are used for the host part.

The number of IP-addresses that can be used for unique hosts is equal to 2^n - 2, where n is the number of bits in the host part. The -2 is because the first and the last IP addresses in a subnet are reserved for the network address and the broadcast address, respectively, and cannot be assigned to hosts. Therefore, in the subnet 192.168.2.128/28, the number of IP-addresses that can be used for unique hosts is 2^4 - 2, which is 14.

References:

IPv4 - Subnetting - Online Tutorials Library

IP Subnet Calculator