What is a subnet mask? and how do I find my subnet mask?

Question

I would also like to know what gateway is? I would also like to know What is DNS1 and DNS2

Answer 1

A subnet mask is what determines what part of the IP address represents the "network" portion, and what part represents the "host" portion.

An IP address is 32 bits, and the most common subnet mask you will probably see is 255.255.255.0. If you write this out in binary, that's 24 '1' bits followed by 8 '0' bits. The network interfaces take an IP address, like 192.168.1.123 and put it through a logical "OR" function with the subnet mask. Any bit "ORed" with a 0 results in 0. So the result of applying the 255.255.255.0 subnet mask with the 192.168.1.123 IP address results in 192.168.1.0. So the network is 192.168.1.0 and the host on that network is 123.

There is much more to IP addressing but this should give you enough to get started and do some searches.

You also asked about a gateway, the term "default gateway" is used to refer to the router that a host will use to communicate beyond the local network where it is attached. If you have a home network with a Linksys or similar router for example, it might be 192.168.1.1 and this would be your default gateway address, the hosts go through that router to get to the Internet and everything else that is not locally connected.

To find your subnetmask, on a Windows PC you can bring up a command window (Start, Run, cmd) and give the command "ipconfig" and you will see your IP address, subnet mask, and default gateway. You can also right-click My Network Places and select Properties, then click on the adapter and the info bar on the left will tell you the address and mask. On a Unix platform, instead of "ipconfig", typically the "ifconfig" command is used.

You also asked about DNS1 and DNS2, these are the Domain Name Server addresses your machine talks to in order to "resolve" a name (like www.yahoo.com) to an IP address (like 216.109.118.77) for example. Computers need to communicate using IP addresses, but we humans much prefer names, and DNS is what handles the conversions. You can do lookups manually if you want to try it. Brng up a command prompt and type "nslookup" to run the nameserver lookup program. And the ">" prompt you can type names, like www.cnn.com, and it will answer you back with IP addresses for that name, give it a try.

Answer 2

A subnet mask is basicly a method to evaluate two IP addresses to assess whether they are on the same community (subnet). As an example, look on the subnet masks of 255.255.255.0 Now convert this to binary: 11111111.11111111.11111111.00000000 anything that's a 1 is a part of the "community section" of the deal with. The zero's differentiate between hosts. Now lets look at a category C community. 192.168.0.Zero/24 11000000.10101000.00000000.00000000 And take the primary two hosts on this subnet, and line them up with the subnet masks. A 1 within the subnet mask compares the corresponding digit of each IP address with an XOR (uncommon OR) operate. 192.168.Zero.1 AND 192.168.0.2 11111111 .11111111. 11111111. 00000000 11000000.10101000.00000000.00000001 11000000.10101000.00000000.00000010 See how the primary three octets in shape? This shows they're on the equal subnet. The subnet mask can handiest be a continuous move of 1's adopted through a circulate of zero's As soon as the first 0 seems within the subnet masks it immediately turns into the host part. Now as for subnet id. Lets take a category B deal with. 172.16.0.Zero/16 The subnet for that is 255.255.0.Zero This offers 65025 IP addresses. Big community eh? However what if we want to subnet it additional. Earlier than we used the subnet masks 11111111.11111111.11111111.00000000 Now lets exchange the 1's into N's (for community) and the zero's into H's (for hosts) NNNNNNNN.NNNNNNNN.NNNNNNNN.HHHHHHHH Or with our new subnet masks NNNNNNNN.NNNNNNNN.HHHHHHHH.HHHHHHHH Lets keep this as simple as viable. We are going to take the deal with 172.Sixteen.0.0 with the subnetmask 255.255.Zero.Zero and create 255 subnets. For this, we minimize the quantity of hosts per subnet, via altering the subnet mask, which we change to the first masks we used of 255.255.255.0. 11111111.11111111.11111111.00000000 Now lets trade them into N's and H's once more. However we will also add S's to show subnet NNNNNNNN.NNNNNNNN.SSSSSSSS.HHHHHHHH Now the 1's of the subnet still need to in shape, but now we use the third octet as the subnet identity. In case you simplest need 2 subnets you would use the mask 255.255.128.0. And in binary: 11111111.11111111.10000000.00000000 or NNNNNNNN.NNNNNNNN.SHHHHHHH.HHHHHHHH Aslong because the subnets in shape, the packet will be sent to the address. If there is a mismatch the packet will be sent to the default gateway, or dropped if no gateway is available. Sorry if that is confusing, i attempted to make it so simple as feasible.

Answer 3

A subnet masks is basicly a strategy to evaluate 2 IP addresses to investigate whether or not they're at the identical community (subnet). As an instance, seem on the subnet masks of 255.255.255.zero Now convert this to binary: 11111111.11111111.11111111.00000000 Anything that is a a million is aspect of the "community phase" of the deal with. The zero's differentiate among hosts. now we could seem at a category C community. 192.168.zero.zero/24 11000000.10101000.00000000.00000000 And take the primary 2 hosts in this subnet, and line them up with the subnet masks. A a million within the subnet masks compares the corresponding digit of every IP deal with with an XOR (eXclusive OR) role. 192.168.zero.a million AND 192.168.zero.two 11111111 .11111111. 11111111. 00000000 11000000.10101000.00000000.00000001 11000000.10101000.00000000.00000010 See how the primary three octets fit? This indicates they're at the identical subnet. The subnet masks can most effective be a steady movement of a million's adopted by way of a movement of zero's As quickly as the primary zero looks within the subnet masks it immediately turns into the host aspect. Now as for subnet ID. Lets take a category B deal with. 172.sixteen.zero.zero/sixteen The subnet for that is 255.255.zero.zero This offers 65025 IP addresses. Big community eh? But what if we wish to subnet it additional. Before we used the subnet masks 11111111.11111111.11111111.00000000 Now we could difference the a million's into N's (for community) and the zero's into H's (for hosts) NNNNNNNN.NNNNNNNN.NNNNNNNN.HHHHHHHH Or with our new subnet masks NNNNNNNN.NNNNNNNN.HHHHHHHH.HHHHHHHH Lets hold this as sensible as viable. We'll take the deal with 172.sixteen.zero.zero with the subnetmask 255.255.zero.zero and create 255 subnets. For this, we minimize the quantity of hosts in line with subnet, by way of replacing the subnet masks, which we difference to the primary masks we used of 255.255.255.zero. 11111111.11111111.11111111.00000000 Now we could difference them into N's and H's once more. But we're going to additionally upload S's to exhibit subnet NNNNNNNN.NNNNNNNN.SSSSSSSS.HHHHHHHH Now the a million's of the subnet nonetheless have to fit, however now we use the 3rd octet because the subnet ID. If you most effective wish two subnets you could use the masks 255.255.128.zero. and in binary: 11111111.11111111.10000000.00000000 or NNNNNNNN.NNNNNNNN.SHHHHHHH.HHHHHHHH Aslong because the subnets fit, the packet might be despatched to the deal with. If there's a mismatch the packet might be despatched to the default gateway, or dropped if no gateway is to be had. Sorry if that is complicated, I attempted to make it as sensible as viable.

Answer 4

These are hard questions... I suggest you start reading some networking books ;-)

If you are just trying to set up an internet account, try DHCP (windows calls it automatic configuration or something). If this works, you should be ready. If it doesn't... your ISP should've given you two DNS server IP numbers that would look like something in this format: 123.123.123.123

Your subnet mask is probably 255.255.255.0 when you are on a local network. If you have only one pc that connects directly (so not behind a router) to the internet, it will be different.

A gateway is a router that connects you from one network to an other in order to connect to a specific range of IP adresses. I don't expect you to understand the latter :p