Question 1

Step 1: Convert the IP Address to Binary

Accepted Answer

We break down the decimal numbers 192.168.1.130 into four 8-bit octets.

Question 2

Step 2: Convert the Subnet Mask to Binary

Accepted Answer

A /26 mask means the first 26 bits are 1s, and the remaining 6 bits are 0s.
The binary mask is: 11111111.11111111.11111111.11000000
Converting this back to decimal gives us the traditional subnet mask: 255.255.255.192.

Question 3

Step 4: Calculate the Broadcast Address

Accepted Answer

To find the Broadcast Address, we take the Network Address and change all the "host bits" (the bits that were 0 in the subnet mask) to 1s. Since the mask had 6 zeros at the end, we change the last 6 bits of the Network Address to 1s.
Network:   11000000.10101000.00000001.10000000
Broadcast: 11000000.10101000.00000001.10111111
Converting the last octet (10111111) to decimal: 128 + 32 + 16 + 8 + 4 + 2 + 1 = 191.
The Broadcast Address is 192.168.1.191.

Question 4

Step 5: Calculate the Usable Host Range

Accepted Answer

The usable hosts are all the addresses mathematically situated between the Network Address and the Broadcast Address. 
First usable host: Network Address + 1 = 192.168.1.129
Last usable host: Broadcast Address - 1 = 192.168.1.190
To verify the total number of usable hosts, we use the formula: $2^n - 2$, where n is the number of host bits (the zeros in the mask). 
$2^6 - 2 = 64 - 2 = 62$ usable hosts. Counting from .129 to .190 exactly equals 62 available IP addresses for devices.

Question 5

What is the "localhost" or 127.0.0.1 address used for?

Accepted Answer

The IP address 127.0.0.1 (and the entire 127.0.0.0/8 block) is strictly reserved as the "loopback" address. It is a virtual IP address that points directly back to the device you are currently using. When a developer builds a website on their laptop and wants to test it without putting it on the internet, they host it locally and navigate to 127.0.0.1. The computer's networking stack intercepts this traffic before it ever hits the physical network card and loops it right back to the internal software. It is the universal networking equivalent of talking to yourself in the mirror.

Question 6

Why do almost all home Wi-Fi routers use addresses that start with 192.168?

Accepted Answer

In 1996, the IETF published RFC 1918, which designated the 192.168.0.0/16 block exclusively for private, internal networks. Because this block contains 65,536 addresses, it was the perfect size for consumer hardware manufacturers (like Linksys, Netgear, and Asus) to use as default settings for home routers. It guarantees that the IP addresses assigned to your phone and laptop will never conflict with the public IP addresses used by servers on the internet. It became an industry standard simply through mass adoption by these hardware vendors in the early 2000s.

Question 7

Can an IP address reveal my exact physical location and identity?

Accepted Answer

No, an IP address cannot pinpoint your exact street address or reveal your name by itself. When someone analyzes your public IP address using a geolocation database, they are mapping it to the Internet Service Provider that owns that block of addresses. This typically reveals the city, state, or general metropolitan area where the ISP's regional data center is located. However, your ISP keeps strict internal logs mapping that IP address to your specific customer account and billing address. Law enforcement can subpoena the ISP to match the IP address to your exact physical identity, but an ordinary website or individual cannot.

Question 8

What is APIPA, and why does my computer sometimes get a 169.254.x.x address?

Accepted Answer

APIPA stands for Automatic Private IP Addressing (also known as Link-Local addressing). If your computer is configured to get an IP address dynamically, but it cannot reach the DHCP server (perhaps the router crashed, or the Ethernet cable is unplugged), the operating system will automatically assign itself an address from the 169.254.0.0/16 block. This is a fail-safe mechanism. It allows devices on the same physical switch to still talk to each other without a router. However, APIPA addresses are strictly non-routable, meaning if you see a 169.254.x.x address, you have fundamentally lost internet connectivity.

Question 9

What is the difference between a /32 subnet and a normal network?

Accepted Answer

A /32 subnet mask (255.255.255.255) means that all 32 bits are dedicated to the network, leaving exactly zero bits for host addresses. Mathematically, a /32 represents a single, specific, isolated computer, rather than a network of computers. This is heavily used in firewall rules and routing tables. If a security engineer wants to block a single malicious hacker's IP address without blocking the rest of the hacker's ISP, they write a firewall rule targeting that specific IP with a /32 mask. It tells the router, "Apply this rule to this exact address, and absolutely no others."

Question 10

Why does IPv6 use letters in its addresses?

Accepted Answer

IPv6 addresses are 128 bits long, which is too massive to display using the decimal numbers (0-9) used in IPv4. To make them shorter and easier to read, IPv6 uses the hexadecimal numbering system. Hexadecimal is a Base-16 system. It uses the numbers 0 through 9 to represent values zero to nine, and the letters A, B, C, D, E, and F to represent the values ten through fifteen. Therefore, the letters in an IPv6 address are not words or code; they are simply mathematical digits representing numbers higher than nine.

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