Newb question. What does the /24 specify? Newb question. What does the /24 specify? Haleon (IS/IT--Management) (OP) 17 Mar 06 18:05 In this example:192.168.1.1/24Is that the subnet or something? What's it called? RE: Newb question. What does the /24 specify? jimbopalmer (Programmer) 17 Mar 06 19:19 /24 indicates the subnet mask is 255.255.255.0in binary, it has 24 1s and 8 0s11111111111111111111111100000000so a /16 would be 255.255.0.011111111111111110000000000000000 I tried to remain child-like, all I acheived was childish. RE: Newb question. What does the /24 specify? KiscoKid (ISP) 18 Mar 06 09:17 a.b.c.d/24 is called CIDR notation. It's Google-able. RE: Newb question. What does the /24 specify? cyberspace (TechnicalUser) 23 Mar 06 11:25 Also, FYI:/24 - Default Class C subnet mask (255.255.255.0)/16 - Default Class B subnet mask (255.255.0.0)/8 - Default Class A subnet mask (255.0.0.0) 'When all else fails.......read the manual' RE: Newb question. What does the /24 specify? wasisnt (IS/IT--Management) 28 Mar 06 19:34 Its just a shortcut way to tell you what the subnet mask is. Free Computer Help and Tips:http://www.onlinecomputertips.com/ RE: Newb question. What does the /24 specify? chieftan (MIS) 31 Mar 06 08:44 CIDR = Classless Inter Domain RoutingOr you could call it VLSMVariable length Subnet MasksEither way, it means you can subnet your network more effectively. RE: Newb question. What does the /24 specify? Haleon (IS/IT--Management) (OP) 31 Mar 06 08:50 Thanks for all the replies, guys!I spent a couple of hours going over subnetting in detail, so I feel comfortable with the general premise of creating custom subnet masks and then referring to the subnets by their subnet IDs, but I still am confused about a couple of things.Is it possible to take a class C address and apply a subnet mask that is less than 24 bits to it? Or can you only ADD bits to a subnet mask?Also, I've seen a network with a private class A address (10.0.0.0) subnetted with a class C default subnet mask. I was under the impression that you could only customize the subnet mask to the next octet in the mask. Can you go even further than that? I appreciate the help guys! RE: Newb question. What does the /24 specify? leedsit (TechnicalUser) 31 Mar 06 09:32 Hi, yup, you could take a Class C address and reduce the mask if you wish, known as Supernetting. and also you can summarize ( CIDR ) address ranges on routers to cover routes for ranges of Class C.I.E192.168.0.0 /24 ( Class C ) = around 254 nodes192.168.1.0 /24 ( Class C ) = around 254 nodesSupernet to192.168.0.0 /23 = around 512 nodes Range192.168.0.0 to192.168.1.254OR192.168.0.0 /22 = around 1024 nodesRange192.168.0.0 to192.168.3.254On a router, If you have 4 class C address routes192.168.0.0 /24192.168.1.0 /24192.168.2.0 /24192.168.3.0 /24Instead of having 4 separate routes in the routing table you could use CIDR and have one entry representing the whole range192.168.0.0 /22Of couse the same applies with class B`s, A`s etc... LEEroyMCNE6,CCNA2,CWNA, Project+ RE: Newb question. What does the /24 specify? jimbopalmer (Programmer) 31 Mar 06 09:33 1) Yes, I have seen clients who, when they ran out of 192.168.1.x addreses, just widened their mask to allow 192.168.0.x to 192.168.7.x addresses2) Yes, a great many 'large' organizations are 10.x.x.x worldwide, although each remote site may use a 255.255.255.0 mask. The local router can send all other 10.x.x.x addresses to Corporate Headquarters and all other addresses to the Internet.So a real estate agenty may be 10.199.237.x and all local devices are in the subnet, but an address like 10.0.100.50 may be a mail server at the world headquarters. By using a 255.255.255.0 mask it knows that the mail server is not local. The local router can have a default route of the internet and a 10.0.0.0/8 route to the main router at corporate.In this scenario, one usually has a VPN back to Corporate (and a firewall to the internet) I tried to remain child-like, all I acheived was childish.