192.168.1.0/25 just means 25 bits in the network portion of the IP address. In a 32 bit address, that means you have 7 bit of space left for the device address part. with 8 bits apiece in each octet, you can figure it out pretty quickly. I've always heard the /## notation referred to as cisco notation. On Mon, Aug 31, 2015 at 8:51 AM, Keith Smith wrote: > > Very nice Kenn!! > > Ok so if I had 192.168.1.0/25 the range would be 192.168.1.0 - > 192.168.1.127 > > /26 would be 192.168.1.0 - 192.168.1.192 ? or is it 192.168.1.0 - > 192.168.1.64 ? > > Is that correct? > > Not sure how to make a net mask out of 192.168.1.0/25 - would it be > 255.255.255.128? > > > Thanks!! > > > > On 2015-08-31 02:55, parabellum7@yahoo.com wrote: > >> Hi Keith, >> >> If I recall correctly, the /24 part of 192.168.0.0/24 is the subnet >> specified in CIDR notation (Classless Inter Domain Routing). >> >> Think in binary terms, that /24 equals >> 11111111.11111111.11111111.00000000 (note there's 24 1's) equals >> 255.255.255.0 so is a class C subnet with the first three octets being >> the network mask. >> >> Likewise if you had an IP addy followed by a /8 that equals >> 11111111.00000000.00000000.00000000 equals 255.0.0.0 so is a class A >> subnet. >> >> Called octets cuz there's 8 bits hence a decimal max of 255. >> >> CIDR is usually seen at ISP's or in enterprise networks that need to >> subnet further as the network mask does not have to align with the >> octet boundary as it does in the classfull network addressing we're >> used to. That's where things get weird and all this because those >> silly routers only speak binary. :] >> >> If you're seeing 192.168.0.0/24 in a zenmap target field it means scan >> everything from and including 192.168.0.0 to 192.168.0.255. >> >> >> IP network classes or Classfull Network Addressing >> >> - Range - - mask - >> # of networks # of nodes CIDR mask >> A 1.1.1.1 - 126.255.255.255 255.0.0.0 >> 126 16,777,214 /8 >> B 128.0.0.1 - 191.255.255.255 255.255.0.0 >> 16,384 65,534 /16 >> C 192.0.0.1 - 223.255.255.255 255.255.255.0 >> 2,097,151 254 /24 >> D 224.0.0.1 - 239.255.255.255 >> E 240.0.0.1 - 255.255.255.255 >> >> >> >> --Kenn >> >> --------------------------------------------------- >> PLUG-discuss mailing list - PLUG-discuss@lists.phxlinux.org >> To subscribe, unsubscribe, or to change your mail settings: >> http://lists.phxlinux.org/mailman/listinfo/plug-discuss >> > > -- > Keith Smith > > --------------------------------------------------- > PLUG-discuss mailing list - PLUG-discuss@lists.phxlinux.org > To subscribe, unsubscribe, or to change your mail settings: > http://lists.phxlinux.org/mailman/listinfo/plug-discuss > -- James McPhee jmcphe@gmail.com