I can't find my workstations !!
Hello At home I have my windows server 2003 installed on my PC with this ip: 192.168.0.10 (server2003) + windows xp professional on 2 notebooks with these ip's: 192.168.0.12 (wsDell) 192.168.1.125 (wsToshiba) The subnet on all 3 machines is 255.255.255.0 and the default gateway is the IP of my router and which is 192.168.0.1 - When I ping for wsDell I find it but I can't find wsToshiba !! why ? * I use server2003 to ping to my workstations !! Can you pleas help me and explain what the problem is??? I can solve this problem by choosing obtain an IP automatically but I just want to use and understand IP configurations. thanks a lot in advance
June 15th, 2008 2:28am

Because the Toshiba is in the wrong IP subnet. With a 24-bit subnet mask (ie 255.255.255.0) the first 24 bits must be identical. Put all the machines in 192.168..0.x or in 192.168.1.x but don't mix the two!Bill
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June 15th, 2008 8:27am

thank you 4 your response! So, the solution is to change the IP of my wsToshiba and yes it works !! .. but is this the only solution ? If my subnetmask is 255.255.255.0 the IP range must be between 2 and and 254 but NOT 255 otherwise it gives me an error: The combination of IP address and subnet mask is invalid. all the bits in the host addresses portion of the IP address are set to 1. Pleas enter a valid combination of IP address and subnet mask. IP = 192.168.0.1 Subnetmask = 255.255.255.0 The host addresses portion = 255 The host addresses portion are set to 1 means : 11111111 True?? - Can you explain me why not 255? -- 255 is for the broadcast, so I can't use it!! right? - What should I do to use my server2003 and my 2 workstations with IP I already used whithout changing the third portion? - Can I change just the subnetmask on my tohiba to get this work? - 192.168.x = class C and this means that we have just 254 hoster per 1 network!! suppose in my home I have 255 computers. The first IP is saved for my router : 192.168.0.1 The 255 host portion for broadcast : 192.168.0.255 This means ====> I have range from 192.168.0.2 to 192.168.0.254 = 252 so I need 2 networks or not? 192.168.0.2 to 192.168.0.254 <<< Network A 192.168.1.0 192.168.1.1 192.168.1.2 for network B So how I should solve this problem to get all the computers connected to each other in 1 lan ? Thank you so much ..
June 15th, 2008 12:42pm

Mostop said: 255 is for the broadcast, so I can't use it!! right? Yes, that's true. The broadcast address in a network is the address where the hostportion contains all 1s.With a 24bit subnetmask (where your subnetmask contains 24 1s and fillsthree octets) the hostportion consists of 8 bits. (the last octet) The subnetmask looks like 255.255.255.0 and the hostportion of the broadcast address looks like x.x.x.255.Thenetwork address in a network is the address where the hostportion contains all 0s. You cannot use the network address (containing all 0s) as well. Mostop said: Can I change just the subnetmask on my tohiba to get this work?No, that will not suffice.If you change the subnetmask on WsToshiba it will know how to send information directly to the other hosts, but the other hosts will respond by sending their information to the router, which in turn doesn't know where WsToshiba is. The subnetmask acts as a filter to determine which information to send directly to a host and which information to send through thedefault gateway. Mostop said: So how I should solve this problem to get all the computers connected to each other in 1 lan ?You should change the subnetmask on allhosts, including yourrouter.This is called supernetting. More information here.In your case a 23bit subnetmask would suffice, which looks like 255.255.254.0.You can use the addresses 192.168.0.2 through 192.168.0.255 and 192.168.1.0 through 192.168.1.254 in the same network.(notice how the host portion of 192.168.0.255does not contain all 1s and how the host portion of 192.168.1.0 does not contain all 0s)
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June 15th, 2008 1:01pm

Dear Sander Berkouwer,I really thank u soo much 4 ur response and I appreciate that but I have some questions about your response:You said :" Thenetwork address in a network is the address where the hostportion contains all 0s. You cannot use the network address (containing all 0s) as well. "So all IP's like:192.186.0.0 192.186.1.0 192.186.2.0 192.186.3.0 ..are network adresses which I can't use because hostportion contains all 0s !!Is that true?You said:"The subnetmask acts as a filter to determine which information to send directly to a host and which information to send through thedefault gateway."If I understand you good, you mean if my subnetmask is 255.255.255.0 and I want to send a message to a certain host it will look for IP's between x.x.x.2 (because 1 is router or gateway and 0 is network address) and x.x.x.254 (because 255 is broadcast) ... AND if my subnetmask is 255.255.254.0 and I want to send a message to a cerrain host it will look for IP's in second network which can be 192.168.254.255 ... is this true ???!!!If my subnetmask is 255.255.0.0 means I have 65.534 hosts (class B for big companies)if subnetmask = 255.0.0.0 means I have 16.777.214 hosts (class A for internet)But what is the meaning of 255.255.254.0Is the meaning that the range of my hosts is 9 bits and so 2^9 = 512 hosts ??192.168.0.2192.168.0.3192.168.0.4..192.168.0.254192.168.1.1192.168.1.2...Is that true ?Thanks again !!
June 15th, 2008 1:46pm

Mostop said: are network adresses which I can't use because hostportion contains all 0s !!Is that true?It might be true.It depends on the subnetmask. The subnetmask defines the networkportion and the hostportion ofan IP address. Mostop said: "The subnetmask acts as a filter to determine which information to send directly to a host and which information to send through the default gateway." If I understand you good, you mean if my subnetmask is 255.255.255.0 and I want to send a message to a certain host it will look for IP's between x.x.x.2 (because 1 is router or gateway and 0 is network address) and x.x.x.254 (because 255 is broadcast) ... AND if my subnetmask is 255.255.254.0 and I want to send a message to a cerrain host it will look for IP's in second network which can be 1More or less.It will send traffic directly to hosts that are on the same network.Since the subnetmask is 255.255.255.0, it will look for hosts on x.x.x.1 (your router), x.x.x.2, x.x.x.3, x.x.x.4.... x.x.x.254The Default Gateway of course is on the same network, else it wouldn't be of much use. Mostop said: If my subnetmask is 255.255.0.0 means I have 65.534 hosts (class B for big companies)if subnetmask = 255.0.0.0 means I have 16.777.214 hosts (class A for internet)But what is the meaning of 255.255.254.0Is the meaning that the range of my hosts is 9 bits and so 2^9 = 512 hosts ??More or less.The 9bit hostportion idea is correct and the 512 hosts count is also theoretically correct.You will actually be able to place 510 hosts on a network with a 23bit (255.255.254.0) subnetmask, since you wouldn't be able to use the networkaddress (hostportion containing9 0s) and the broadcast address (hostportion containing 9 1s)The link I provided earlier clearly describes this. Mostop said: 192.168.0.2192.168.0.3192.168.0.4..192.168.0.254192.168.1.1192.168.1.2...192.168.1.254This sounds true, but then you wouldn't be using 2 addresses which you can use: 192.168.0.255 address: 111111111111111111111110 11111111 networkportion:11111111111111111111111 hostportion: 0 11111111 (not all 1s, so not a broadcast address) 192.168.1.0 address: 111111111111111111111111 00000000 networkportion:11111111111111111111111 hostportion: 1 00000000 (not all 0s, so not a network address)
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June 15th, 2008 2:21pm

Thank you my dear ..I am now busy making an exercice to test myself if I understand these bits and ip counting ..If I answer wrong pleas correct me ..Thank you soo much ..
June 15th, 2008 3:13pm

Exercice number 1:Given:2 PC's: PC1 and PC2PC1: IP = 86.112.73.190Subnet = 255.255.255.192PC2:IP = 86.112.73.193Subnet = 255.255.255.192Question:Do both PC's exit in the same network? Why?My Answer:Yes because the first 24-bits (86.112.73) are the same !!
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June 15th, 2008 3:22pm

Mostop said: Exercice number 1:Given:2 PC's: PC1 and PC2PC1:IP = 86.112.73.190Subnet = 255.255.255.192PC2:IP = 86.112.73.193Subnet = 255.255.255.192Question: Do both PC's exit in the same network? Why?My Answer:Yes because the first 24-bits (86.112.73) are the same !! They're not in the same network though.255.255.255.192 indicates a 26bit subnetmask, which means the first 26 bits ofboth IP addresses need to be the same to be considered on the same network. The first 26 bits indicate the networkportion.Both addresses can be seen as:(networkportion in red, hostportion in green) 86.112.73.190 (01010110 0111000 01001001 10111110) 86.112.73.193(01010110 0111000 01001001 11000001) You can clearly see the difference in the networkportion of both addresses.Hence the addresses or not on the same network.
June 15th, 2008 3:44pm

my dear Sander192 in binary is 11000000so why should 25 bit 1 and 26 0 ?
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June 15th, 2008 4:14pm

I think I get itSubnet = 255.255.255.192 means11111111.11111111.11111111.11000000hier we see that the subnet indicates 26-bit11111111.11111111.11111111.00000000this is 255.255.255.0 = 24-bitIs this true ??!!If we want to know if different IP's from the same network , we have to compare with bits of subnet.255.255.255.128 ===> 25-bit11111111.11111111.11111111.10000000 ==> 25-bitBUT 255.255.255.86 does not work and gives an error which says: "You entred an invalid subnet mask. The subnet mask has to be contiguous. Pleas enter a valid one"That is bacause 86 does not start with 0 !!!Is this all true ?
June 15th, 2008 5:01pm

This is turning out to be quitea slow chat ;-)Let me try to make things a bit more clear, before we start to confuse things: An IP address consists of 4 bytes of 8 bits each. In totalan IP address contains 32 bits A Subnet Mask consists of the same 4 bytes, but when looking at a binary Subnet Mask, italways exists of a series of contiguous 1s. A Subnet Mask masks the bits of an IP address, marking it as the network portion of the IP address. * If the network portion of two IP addresses are identical,the hosts with these IP addresses belong to the same network. If two hosts belong to the same network, information is exchanged directly. If two hosts do not belong to the same network, information is exchange through default gateway(s) * I used red in my previous post to mark the network portion. Mostop said: I think I get it Subnet = 255.255.255.192 means 11111111.11111111.11111111.11000000hier we see that the subnet indicates 26-bit 11111111.11111111.11111111.00000000 this is 255.255.255.0 = 24-bit You got it! Mostop said: If we want to know if different IP's from the same network , we have to compare with bits of subnet. You got it! Mostop said: 255.255.255.86 does not work and gives an error which says: "You entred an invalid subnet mask. The subnet mask has to be contiguous. Pleas enter a valid one" That is bacause 86 does not start with 0 !!! Since a Subnet Mask needs to be a contiguous series of 1s, 255.255.255.86 is not a valid Subnet MaskThe binary equivalent of 86 is 01010110, which starts with a 0 and has 0s between the 1s.
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June 15th, 2008 5:10pm

a slow chat yes :-) thank u very much .. i understand now the problem.!I am going 4 second exercice :)
June 15th, 2008 6:55pm

I have a PC1 with fallowing configurations: IP address : 10.120.240.148 Subnetmask : 255.255.252.0 Default gateway : 10.120.240.250 Question: PC1 send a ping to PC2; what is the followed way of the ping packets in the case if the subnet mask is: 255.255.252.0 ??? What then if you change subnetmasker to: 255.255.254.0 ???255.255.252.011111111.11111111.11111100.00000000 (22-bit)255.255.254.011111111.11111111.11111110.00000000 (23-bit) 10.120.240.25000001010.01111000.11110000.11111010 10.120.240.14800001010.01111000.11110000.10010100My answer:If I use the subnetmask (23-bit) the ping will be sent directly to PC2 but it will and the other case will send ping by sending it to the router !!True ??!
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June 15th, 2008 7:43pm

I'm sorry, but I don't seem to be able to understand the exercise.What's the IP Address and Subnet Mask for PC 2?
June 17th, 2008 1:29pm

Hi dearNo, there is no IP or subnetmask mentioned for the PC2.Only PC1 and just 1 sunbet and the IP of router!!
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June 17th, 2008 3:14pm

Up :)
June 18th, 2008 8:44pm

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