Mastodawn

3/4
🔹 Segmento IP (Capa 3): La dirección postal
Aquí es donde entran las direcciones IP y las máscaras de subred (192.168.1.0/24). Mientras la VLAN separa, el Segmento IP permite que los dispositivos se identifiquen y sepan hacia dónde enviar los paquetes.
Regla de oro: Casi siempre asignamos un Segmento IP distinto a cada VLAN, pero siguen viviendo en capas diferentes del modelo OSI. 💡
#IPAddress #Subnetting #Infraestructura

Marcos Nov 18

For those folks who are studying networking for their #CCNA or other related networking certification and need practce questions for #subnetting, I always used to like subnettingquestions.com, and I'd say if you can solve them in your head in 10 seconds or less, you''re doing pretty good. BUT, I recently stumbled on subnettingpractice.com which feels like it has more real world scenarios in the questions. Feels a little harder to me, but also good to be able to solve them quickly and in your head. Good stuff!

Nuria Nov 2

Mein neuer, zusätzlicher Router ist scharf geschaltet und die Config mit 95% fast fertig 🫶

Manchmal muss man das Netzwerk einfach neu strukturieren. Es gibt Dinge, die mag man nicht in jedem Protokoll haben 🏹 Besser getrennt und klar definiert. So arbeitet man sauber, das Netz ist so auch übersichtlicher und strukturierter 🖤

#DSGVO
#Subnetting
#ITSecurity
#NetzwerkArchitektur
#iot
#portforwarding
#stealth

Lucio Sep 17, 2025

Ever tried to find one specific book from inside a ginormous, single-roomed library? That's a network without subnets. Subnetting (FLSM/VLSM) is like having sections, floors, and aisles. CIDR notation (/24) is the library plan. It brings order to chaos, making routing efficient and secure. I finally "got it" when I started thinking binary. It's gorgeous, I promise!

#Networking #Subnetting #CIDR #SysAdmin #TechTalk

aaron ~#

Aug 1, 2025

Managing #OpenWRT via #Ansible is a breeze. I just love the fact that all the settings, all the #firewall rules, all the good stuff is configured with config files.

I've created 6 #VLANs, all of them completely #isolated, with a few allowed traffic rules. I've even isolated the #Windows #PC of my roommate inside of the #trusted #network.

Now his #XiaomiTVBox can't scan the network anymore (yes it actually does that. I've noticed it while working on my packet monitoring project).

#networking #subnetting #subnet #homelab #selfhosting #openwrt #privacy #security #vlan #isolation #dmz

Yetkin Degirmenci 🍫May 2, 2025

Simple Subnet Calculator
Just in case you are also bored to calculate on paper...
#automate #python #subnetting

https://github.com/yetkind/Subnet-Calculator

GitHub - yetkind/Subnet-Calculator: Simple Subnet Calculator for System Administrators.

Simple Subnet Calculator for System Administrators. - yetkind/Subnet-Calculator

GitHub

KSev 🇳🇴🌻🚲Jan 24, 2025

The most relevant IT certification content I ever studied was Cisco CCENT.
Sadly, Cisco has since abandoned that training. But I will continue to place it #1 in what I'd like a tech starting in IT to know. Learn that stuff and you're golden with me; It proves to me you can learn and have the wherewithal to succeed in IT.
#CCENT #IPAddressing #Subnetting #Routing

Chris Woody Woodruff Jan 5, 2025

Ever wondered how devices seamlessly communicate across the digital world?

Learn about IPv4 vs. IPv6, the magic of subnet masks, and how CIDR notation keeps networks organized and optimized.

Read the blog post here: https://woodruff.dev/decoding-ip-addressing-and-subnetting-the-backbone-of-networking/

#Networking #IPAddresses #Subnetting

Decoding IP Addressing and Subnetting – The Backbone of Networking - Chris Woody Woodruff

In today's hyper-connected world, where everything from your smartphone to your coffee machine can be online, understanding networking is no longer just for IT pros. At the heart of all this connectivity lies IP addressing and subnetting—the unsung heroes of the digital age. These concepts are the foundation of how devices communicate and share data seamlessly across networks, ensuring everything works. But how does it all happen? Let's break it down.

Chris Woody Woodruff - Just Stuff from Woody

The Wiert Corner - irregular stream of stuff Nov 27, 2024

IPv4 subnet/CIDR table from OccupytheWeb on Twitter: “Network Basics for Hackers: Subnetting, Subnet Masks and CIDR Notation …”

I wrote about programs and scripts doing IPv4 subnet calculation, but sometimes it is easier to have a table at hand, so here is the one I found at [Wayback/Archive] OccupytheWeb on Twitter: “Network Basics for Hackers: Subnetting, Subnet Masks and CIDR Notation #networks #networkbasics #subnetting #infosec #networks4hackers #cyberwarrior #cyberwarrior #networkbasics #networkbasics subnet”

Notes:

it is by far original, as a quick image search revealed lots of other sources, for instance the 2011 post [Wayback/Archive] Subnet Mask Quick Reference | Academic PCs Blog
there is a much better table below adapted from Classless Inter-Domain Routing: IPv4 CIDR blocks – Wikipedia

Some earlier related posts:

And another example where the same table was used: [Wayback/Archive] tcpip – How to understand the “A subnet Example”? – Server Fault.

Since this one from Classless Inter-Domain Routing: IPv4 CIDR blocks – Wikipedia is much better, I copied it in full then colourised it using the above scheme and added the mask octet and binary mask columns, then added the “(max hosts)” to the “Decimal” columns:

IPv4 CIDR blocks

Address
formatDifference
to last addressMaskMask
octetBinary mask
in octetAddressesRelative
to class
A, B, CRestrictions
on a, b, c and d
(0..255 unless noted)Typical useDecimal
(max hosts)2na.b.c.d/32+0.0.0.0255.255.255.2554111111111201⁄256 CHost routea.b.c.d/31+0.0.0.1255.255.255.2544111111102211⁄128 Cd = 0 … (2n) … 254Point-to-point links (RFC 3021)a.b.c.d/30+0.0.0.3255.255.255.2524111111004221⁄64 Cd = 0 … (4n) … 252Point-to-point links (glue network)a.b.c.d/29+0.0.0.7255.255.255.2484111110008231⁄32 Cd = 0 … (8n) … 248Smallest multi-host networka.b.c.d/28+0.0.0.15255.255.255.24041111000016241⁄16 Cd = 0 … (16n) … 240Small LANa.b.c.d/27+0.0.0.31255.255.255.2244111000003225⅛ Cd = 0 … (32n) … 224a.b.c.d/26+0.0.0.63255.255.255.1924110000006426¼ Cd = 0, 64, 128, 192a.b.c.d/25+0.0.0.127255.255.255.12841000000012827½ Cd = 0, 128Large LANa.b.c.0/24+0.0.0.255255.255.255.0311111111256281 Ca.b.c.0/23+0.0.1.255255.255.254.0311111110512292 Cc = 0 … (2n) … 254a.b.c.0/22+0.0.3.255255.255.252.03111111001,0242104 Cc = 0 … (4n) … 252Small businessa.b.c.0/21+0.0.7.255255.255.248.03111110002,0482118 Cc = 0 … (8n) … 248Small ISP/ large businessa.b.c.0/20+0.0.15.255255.255.240.03111100004,09621216 Cc = 0 … (16n) … 240a.b.c.0/19+0.0.31.255255.255.224.03111000008,19221332 Cc = 0 … (32n) … 224ISP/ large businessa.b.c.0/18+0.0.63.255255.255.192.031100000016,38421464 Cc = 0, 64, 128, 192a.b.c.0/17+0.0.127.255255.255.128.031000000032,768215128 Cc = 0, 128a.b.0.0/16+0.0.255.255255.255.0.021111111165,536216256 C = Ba.b.0.0/15+0.1.255.255255.254.0.0211111110131,0722172 Bb = 0 … (2n) … 254a.b.0.0/14+0.3.255.255255.252.0.0211111100262,1442184 Bb = 0 … (4n) … 252a.b.0.0/13+0.7.255.255255.248.0.0211111000524,2882198 Bb = 0 … (8n) … 248a.b.0.0/12+0.15.255.255255.240.0.02111100001,048,57622016 Bb = 0 … (16n) … 240a.b.0.0/11+0.31.255.255255.224.0.02111000002,097,15222132 Bb = 0 … (32n) … 224a.b.0.0/10+0.63.255.255255.192.0.02110000004,194,30422264 Bb = 0, 64, 128, 192a.b.0.0/9+0.127.255.255255.128.0.02100000008,388,608223128 Bb = 0, 128a.0.0.0/8+0.255.255.255255.0.0.011111111116,777,216224256 B = ALargest IANA block allocationa.0.0.0/7+1.255.255.255254.0.0.011111111033,554,4322252 Aa = 0 … (2n) … 254a.0.0.0/6+3.255.255.255252.0.0.011111110067,108,8642264 Aa = 0 … (4n) … 252a.0.0.0/5+7.255.255.255248.0.0.0111111000134,217,7282278 Aa = 0 … (8n) … 248a.0.0.0/4+15.255.255.255240.0.0.0111110000268,435,45622816 Aa = 0 … (16n) … 240a.0.0.0/3+31.255.255.255224.0.0.0111100000536,870,91222932 Aa = 0 … (32n) … 224a.0.0.0/2+63.255.255.255192.0.0.01110000001,073,741,82423064 Aa = 0, 64, 128, 192a.0.0.0/1+127.255.255.255128.0.0.01100000002,147,483,648231128 Aa = 0, 1280.0.0.0/0+255.255.255.2550.0.0.00000000004,294,967,296232256 AEntire IPv4 Internet, default route.

If you want to modify the table even further, please fork https://gist.github.com/jpluimers/d2665ef16ed20ec9b8266bf154c56830

For now it is hosted as HTML page at https://gist.githack.com/jpluimers/d2665ef16ed20ec9b8266bf154c56830/raw/27cd4c0583771198c65e68f21ee9968c1af64827/IPv4-CIDR-blocks.html

I posted a bitmap of it at [Wayback/Archive] Jeroen Wiert Pluimers on Twitter: “@three_cube For now the HTML is served at …”

–jeroen

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<html xmlns="http://www.w3.org/1999/xhtml" lang="en" class="wf-inactive"><head profile="http://gmpg.org/xfn/11"><body><h1>IPv4 CIDR blocks</h1><table class="wikitable" rules="all"><tbody><tr><th rowspan="2">Address format</th><th rowspan="2">Difference to last address</th><th rowspan="2">Mask</th><th rowspan="2">Mask octet</th><th rowspan="2">Binary mask in octet</th><th colspan="2">Addresses</th><th rowspan="2">Relative to class A, B, C</th><th rowspan="2">Restrictions on a, b, c and d (0..255 unless noted)</th><th rowspan="2">Typical use</th></tr><tr><th>Decimal (max hosts)</th><th bgcolor="lightgreen">2n</th></tr><tr bgcolor="lightyellow"><td>a.b.c.d/32</td><td>+0.0.0.0</td><td>255.255.255.255</td><td>4</td><td>11111111</td><td>1</td><td>20</td><td>1⁄256 C</td><td></td><td>Host route</td></tr><tr><td>a.b.c.d/31</td><td>+0.0.0.1</td><td>255.255.255.254</td><td>4</td><td>11111110</td><td>2</td><td bgcolor="lightgreen">21</td><td>1⁄128 C</td><td>d = 0 … (2n) … 254</td><td>Point-to-point links (<a class="mw-redirect" title="RFC (identifier)" href="https://en.wikipedia.org/wiki/RFC_(identifier)">RFC</a> <a class="external text" href="https://datatracker.ietf.org/doc/html/rfc3021" rel="nofollow">3021</a>)</td></tr><tr><td>a.b.c.d/30</td><td>+0.0.0.3</td><td>255.255.255.252</td><td>4</td><td>11111100</td><td>4</td><td bgcolor="lightgreen">22</td><td>1⁄64 C</td><td>d = 0 … (4n) … 252</td><td>Point-to-point links (glue network)</td></tr><tr><td>a.b.c.d/29</td><td>+0.0.0.7</td><td>255.255.255.248</td><td>4</td><td>11111000</td><td>8</td><td bgcolor="lightgreen">23</td><td>1⁄32 C</td><td>d = 0 … (8n) … 248</td><td>Smallest multi-host network</td></tr><tr><td>a.b.c.d/28</td><td>+0.0.0.15</td><td>255.255.255.240</td><td>4</td><td>11110000</td><td>16</td><td bgcolor="lightgreen">24</td><td>1⁄16 C</td><td>d = 0 … (16n) … 240</td><td rowspan="3">Small <a class="mw-redirect" title="LAN" href="https://en.wikipedia.org/wiki/LAN">LAN</a></td></tr><tr><td>a.b.c.d/27</td><td>+0.0.0.31</td><td>255.255.255.224</td><td>4</td><td>11100000</td><td>32</td><td bgcolor="lightgreen">25</td><td>⅛ C</td><td>d = 0 … (32n) … 224</td></tr><tr><td>a.b.c.d/26</td><td>+0.0.0.63</td><td>255.255.255.192</td><td>4</td><td>11000000</td><td>64</td><td bgcolor="lightgreen">26</td><td>¼ C</td><td>d = 0, 64, 128, 192</td></tr><tr><td>a.b.c.d/25</td><td>+0.0.0.127</td><td>255.255.255.128</td><td>4</td><td>10000000</td><td>128</td><td bgcolor="lightgreen">27</td><td>½ C</td><td>d = 0, 128</td><td rowspan="2">Large <a class="mw-redirect" title="LAN" href="https://en.wikipedia.org/wiki/LAN">LAN</a></td></tr><tr bgcolor="lightyellow"><td>a.b.c.0/24</td><td>+0.0.0.255</td><td>255.255.255.0</td><td>3</td><td>11111111</td><td>256</td><td>28</td><td>1 C</td><td></td></tr><tr><td>a.b.c.0/23</td><td>+0.0.1.255</td><td>255.255.254.0</td><td>3</td><td>11111110</td><td>512</td><td bgcolor="lightgreen">29</td><td>2 C</td><td>c = 0 … (2n) … 254</td><td></td></tr><tr><td>a.b.c.0/22</td><td>+0.0.3.255</td><td>255.255.252.0</td><td>3</td><td>11111100</td><td>1,024</td><td bgcolor="lightgreen">210</td><td>4 C</td><td>c = 0 … (4n) … 252</td><td>Small business</td></tr><tr><td>a.b.c.0/21</td><td>+0.0.7.255</td><td>255.255.248.0</td><td>3</td><td>11111000</td><td>2,048</td><td bgcolor="lightgreen">211</td><td>8 C</td><td>c = 0 … (8n) … 248</td><td rowspan="2">Small <a class="mw-redirect" title="ISP" href="https://en.wikipedia.org/wiki/ISP">ISP</a>/ large business</td></tr><tr><td>a.b.c.0/20</td><td>+0.0.15.255</td><td>255.255.240.0</td><td>3</td><td>11110000</td><td>4,096</td><td bgcolor="lightgreen">212</td><td>16 C</td><td>c = 0 … (16n) … 240</td></tr><tr><td>a.b.c.0/19</td><td>+0.0.31.255</td><td>255.255.224.0</td><td>3</td><td>11100000</td><td>8,192</td><td bgcolor="lightgreen">213</td><td>32 C</td><td>c = 0 … (32n) … 224</td><td rowspan="3"><a class="mw-redirect" title="ISP" href="https://en.wikipedia.org/wiki/ISP">ISP</a>/ large business</td></tr><tr><td>a.b.c.0/18</td><td>+0.0.63.255</td><td>255.255.192.0</td><td>3</td><td>11000000</td><td>16,384</td><td bgcolor="lightgreen">214</td><td>64 C</td><td>c = 0, 64, 128, 192</td></tr><tr><td>a.b.c.0/17</td><td>+0.0.127.255</td><td>255.255.128.0</td><td>3</td><td>10000000</td><td>32,768</td><td bgcolor="lightgreen">215</td><td>128 C</td><td>c = 0, 128</td></tr><tr bgcolor="lightyellow"><td>a.b.0.0/16</td><td>+0.0.255.255</td><td>255.255.0.0</td><td>2</td><td>11111111</td><td>65,536</td><td>216</td><td>256 C = B</td><td></td><td></td></tr><tr><td>a.b.0.0/15</td><td>+0.1.255.255</td><td>255.254.0.0</td><td>2</td><td>11111110</td><td>131,072</td><td bgcolor="lightgreen">217</td><td>2 B</td><td>b = 0 … (2n) … 254</td><td></td></tr><tr><td>a.b.0.0/14</td><td>+0.3.255.255</td><td>255.252.0.0</td><td>2</td><td>11111100</td><td>262,144</td><td bgcolor="lightgreen">218</td><td>4 B</td><td>b = 0 … (4n) … 252</td><td></td></tr><tr><td>a.b.0.0/13</td><td>+0.7.255.255</td><td>255.248.0.0</td><td>2</td><td>11111000</td><td>524,288</td><td bgcolor="lightgreen">219</td><td>8 B</td><td>b = 0 … (8n) … 248</td><td></td></tr><tr><td>a.b.0.0/12</td><td>+0.15.255.255</td><td>255.240.0.0</td><td>2</td><td>11110000</td><td>1,048,576</td><td bgcolor="lightgreen">220</td><td>16 B</td><td>b = 0 … (16n) … 240</td><td></td></tr><tr><td>a.b.0.0/11</td><td>+0.31.255.255</td><td>255.224.0.0</td><td>2</td><td>11100000</td><td>2,097,152</td><td bgcolor="lightgreen">221</td><td>32 B</td><td>b = 0 … (32n) … 224</td><td></td></tr><tr><td>a.b.0.0/10</td><td>+0.63.255.255</td><td>255.192.0.0</td><td>2</td><td>11000000</td><td>4,194,304</td><td bgcolor="lightgreen">222</td><td>64 B</td><td>b = 0, 64, 128, 192</td><td></td></tr><tr><td>a.b.0.0/9</td><td>+0.127.255.255</td><td>255.128.0.0</td><td>2</td><td>10000000</td><td>8,388,608</td><td bgcolor="lightgreen">223</td><td>128 B</td><td>b = 0, 128</td><td></td></tr><tr bgcolor="lightyellow"><td>a.0.0.0/8</td><td>+0.255.255.255</td><td>255.0.0.0</td><td>1</td><td>11111111</td><td>16,777,216</td><td>224</td><td>256 B = A</td><td></td><td>Largest <a title="Internet Assigned Numbers Authority" href="https://en.wikipedia.org/wiki/Internet_Assigned_Numbers_Authority">IANA</a> block allocation</td></tr><tr><td>a.0.0.0/7</td><td>+1.255.255.255</td><td>254.0.0.0</td><td>1</td><td>11111110</td><td>33,554,432</td><td bgcolor="lightgreen">225</td><td>2 A</td><td>a = 0 … (2n) … 254</td><td></td></tr><tr><td>a.0.0.0/6</td><td>+3.255.255.255</td><td>252.0.0.0</td><td>1</td><td>11111100</td><td>67,108,864</td><td bgcolor="lightgreen">226</td><td>4 A</td><td>a = 0 … (4n) … 252</td><td></td></tr><tr><td>a.0.0.0/5</td><td>+7.255.255.255</td><td>248.0.0.0</td><td>1</td><td>11111000</td><td>134,217,728</td><td bgcolor="lightgreen">227</td><td>8 A</td><td>a = 0 … (8n) … 248</td><td></td></tr><tr><td>a.0.0.0/4</td><td>+15.255.255.255</td><td>240.0.0.0</td><td>1</td><td>11110000</td><td>268,435,456</td><td bgcolor="lightgreen">228</td><td>16 A</td><td>a = 0 … (16n) … 240</td><td></td></tr><tr><td>a.0.0.0/3</td><td>+31.255.255.255</td><td>224.0.0.0</td><td>1</td><td>11100000</td><td>536,870,912</td><td bgcolor="lightgreen">229</td><td>32 A</td><td>a = 0 … (32n) … 224</td><td></td></tr><tr><td>a.0.0.0/2</td><td>+63.255.255.255</td><td>192.0.0.0</td><td>1</td><td>11000000</td><td>1,073,741,824</td><td bgcolor="lightgreen">230</td><td>64 A</td><td>a = 0, 64, 128, 192</td><td></td></tr><tr><td>a.0.0.0/1</td><td>+127.255.255.255</td><td>128.0.0.0</td><td>1</td><td>10000000</td><td>2,147,483,648</td><td bgcolor="lightgreen">231</td><td>128 A</td><td>a = 0, 128</td><td></td></tr><tr bgcolor="lightyellow"><td>0.0.0.0/0</td><td>+255.255.255.255</td><td>0.0.0.0</td><td>0</td><td>00000000</td><td>4,294,967,296</td><td>232</td><td>256 A</td><td></td><td>Entire IPv4 Internet, <a title="Default route" href="https://en.wikipedia.org/wiki/Default_route">default route</a>.</td></tr></tbody></table></body></html> view raw

IPv4-CIDR-blocks.html

hosted with ❤ by GitHub

#cyberwarrior #infosec #networkbasics #networks #networks4hackers #subnetting

MikroTik Users Sep 26, 2024

Lab 6.1 - Calculating Subnets
https://zpr.io/purEnNBBzkek
Learn how to calculate subnet addresses, network, and broadcast addresses, and identify the subnet an IP belongs to using an IP address and subnet mask. Master subnetting with simple steps and clear examples! #Networking #Subnetting #IPv4 #Mikrotik

Lab 6.1 - Calculating Subnets

Learn how to calculate subnet addresses, network, and broadcast addresses, and identify the subnet an IP belongs to using an IP address and subnet mask. Master subnetting with simple steps and clear examples! #Networking #Subnetting #IPv4 #Mikrotik

Mikrotik Users