We should probably get rid of the term “subnet” and just tell people the netmask tells you how many of the 32 bits in the (IPv4) address specify the network, with the remaining bits specifying the host. The idea of network/subnet/host goes back to pre-CIDR days.
It doesn’t take long before you instinctively know to subtract from 256. So for a 255.255.255.248 netmask, you subtract 248 from 256 and get 8 which is the number of host addresses. Or if you are dealing with slash notation, /29 means the first 29 of the 32 bits specify the network, so the remaining 32-29=3 bits specify the host. And 2^3=8 is the number of possible host addresses in that network. The concept of network and broadcast address is a little trickier, because it depends on how the IP block will be used. If it’s not an actual LAN (like maybe being assigned as individual /32 routes via PPPoE), they are usable, but it may confuse people. From: Justin Wilson - MTIN Sent: Tuesday, November 10, 2015 11:15 AM To: [email protected] Subject: Re: [AFMUG] Subnetting and TCP/IP Intro There are some good CCNA videos on Youtube about subnetting. Subnetting is like the old multiplication tables in school. If you memorize what subnet mask corresponds to, say a /29, then you are ahead of the game. Getting down into the binary aspect of it is helpful in about .01% of all troubleshooting on a non-programmer level. If we go back to our math analogy the only place most folks don’t use calculators is on tests. Same with subletting. There are subnet calculators out there for you to use. As long as you understand the fundamentals and know whats going on you don’t have to do all the work manually. The short answer is, even for the mikrotik tests, tell your employee to google “CCNA subletting” on youtube. Lots of good videos in the first 10 choices. After that have them learn the 7 layer OSI model. https://www.youtube.com/watch?v=l_OPR2yh2co Justin Wilson [email protected] --- http://www.mtin.net Owner/CEO xISP Solutions- Consulting – Data Centers - Bandwidth http://www.midwest-ix.com COO/Chairman Internet Exchange - Peering - Distributed Fabric On Nov 10, 2015, at 11:17 AM, Josh Luthman <[email protected]> wrote: Pretty sure this is the site that Butch himself recommended ages ago: http://www.tcpipguide.com/ Josh Luthman Office: 937-552-2340 Direct: 937-552-2343 1100 Wayne St Suite 1337 Troy, OH 45373 On Tue, Nov 10, 2015 at 11:14 AM, Matt <[email protected]> wrote: Have an employee we plan on sending to Mikrotik MTCNA training in next month or two. Prerequisites state: "The student must have a good understanding of TCP/IP and subnetting". Are there some good online youtube or other free sources for this that anyone here recommends?
