A subnetwork, or subnet, is a logically visible subdivision of an IP network.

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33
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5answers
81k views

What is the difference between a VLAN and a subnet? [closed]

I have read numerous forums and articles regarding VLANs and subnets. However, I haven't understood the functions of each apart from the following: Subnets allow the segmentation of a network VLANs ...
21
votes
8answers
18k views

Why do we need subnet mask?

Since a IPv4 address already gives the information of the network and and host, why do we still need a subnet mask? The 1st Octet already specify the network class (1-127: A, 128-191: B, 192-223: C ...
12
votes
7answers
11k views

Why is my subnet mask 255.255.255.255?

I have a modem which used for internet broadband and I got an IP address in the 'A' class 10.x.x.x and have netmask 255.255.255.255. What does 255.255.255.255 mean exactly? When I try to sniff with ...
9
votes
5answers
6k views

What are the essentials of a Subnet mask?

What is the use of a subnet mask? What is the below output conveying to the user? Connection-specific DNS Suffix . : IP Address. . . . . . . . . . . . : 192.168.1.2 Subnet Mask . . . . . . . . . ...
9
votes
4answers
797 views

How to put two subnets next to each other?

I've been using this calculator http://www.subnet-calculator.com/cidr.php, and I'm trying to figure out how to put two different subnets next to each other. For example, I want to have a /27 subnet ...
7
votes
2answers
12k views

What is the difference between a subnet mask and a netmask?

Is there any logic in using two different names for determining host ID and net ID? For example, if you type print route in a Command Prompt you get things with netmask, but the IPv4 settings seems ...
7
votes
1answer
3k views

Is there any reason to subnet a home network?

For networks I understand we set a netmask on each computer to let it know what IPs it can talk to without going through the router - IPs on the same subnet can talk directly to each other and do not ...
6
votes
6answers
30k views

Set up two (2) IP addresses on the same network card?

I think it is possible to set up 2 IP addresses and subnet masks on one NIC in Windows XP. How can this be done?
6
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2answers
6k views

How do I join two subnets with two DD-WRT routers?

I have two separate DD-WRT routers which I would like to bridge together so that computers connected to each are on the same subnet (so that multicast can work between them for UPNP/DNLA media ...
5
votes
3answers
5k views

Why subnet mask for IP 10.0.1.4 is 255.255.255.0?

Well I'm not sure whether I'm missing something here. But all I've read is that if first octet of IP is within 0 - 127 then it is categorized as Class A subnet and correspondingly Subnet Mask for ...
4
votes
5answers
3k views

Where are addresses from the network 0.0.0.0/8 used in practice?

I read that this pool: Means "these hosts" in "this network" Is used for self-identification Is used for broadcast messages My questions are: Where exactly these addresses can be found? Which ...
4
votes
2answers
1k views

How can I find any domain name that resolves to IP within a given net range?

For example, given the range: 172.128.0.0 - 172.191.255.255 I need to find some domain that resolves to an IP-adress within the range. Is it possible ? I'm using a Linux system.
4
votes
2answers
9k views

How to create a separate subnet for wireless access?

I need to configure my wireless router so all wireless devices are on a different subnet (192.168.2.1). The wireless devices should be able to access the internet, but ideally not the workstations on ...
3
votes
2answers
1k views

Windows XP doesn't like small subnets?

This totally sounds like a bug to me, because my subnet mask and IP address should be valid by all accounts. My ISP has assigned me a fixed IP address of 65.110.7.20, with a subnet mask of ...
3
votes
2answers
2k views

Changing Mac OS X 10.6 Routing after VPN'd In

I have a coffee shop around the corner that I use to do some work when I want to get away from home. They offer free wi-fi and I then use my Mac 10.6 VPN to log into my work network. I have "Send all ...
3
votes
2answers
3k views

I'm using Cisco Packet Tracer for Simulation and got error “ip address overlaps with..etc”

The 1st row is for my router and the 2nd row is for my LAN. What's wrong? Is my IP addressing and subnetting wrong? I already checked my configuration.
3
votes
1answer
204 views

Understanding the black magic of IPv6 addresses

my router (AVM Fritz Box) is supporting 6to4. So far it works but I want to understand what's going on. The last few hours I spent on a IPv6 book. There are many things I understand now but there is ...
3
votes
2answers
784 views

route lan traffic through wirless mifi

I have a Windows 7 laptop accessing the internet through Verizon wireless MIFI configured as 192.168.1.1. It supports only 5 wireless connections, so I don't want to use up connections unnecessarily. ...
3
votes
2answers
28 views

Does a typical home router support classless IP address?

All typical home routers I know of allow us to set a custom subnet mask, and because of this, I am really curious about whether they support the use of classless addressing scheme, meaning that in the ...
3
votes
1answer
616 views

How to calculate CIDR notation from entries in a routing table

I have some entries in a routing table that were created using longest prefix matching, and I have to use those entries to determine the a.b.c.d/x notation (CIDR). This is an example entry: 11001000 ...
3
votes
1answer
1k views

Home network with two routers and just one Wifi

I know it is a pretty lame question, but I am not a pro in networking, so I will still ask it. And I will try to explain details where possible. I want to create the following setup: Phone line is ...
2
votes
5answers
9k views

Can you have a class C IP address with a subnet mask of 255.255.0.0?

Can you have a class C IP address with a subnet mask of 255.255.0.0? What happens when you have a setting like this?
2
votes
2answers
710 views

How does CIDR slow the exhaustion of IPv4?

In the Wikipedia article on CIDR, it says The Internet Engineering Task Force introduced CIDR in 1993 to replace the previous addressing architecture of classful network design in the ...
2
votes
2answers
3k views

Is 225.225.225.128 a valid subnet mask?

I have been told that we have two devices on a network: 10.40.225.142 and 10.40.225.144 These devices both have Gateway 10.40.225.129 Subnet mask 225.225.225.128 (note 225 is Not a typo) These ...
2
votes
2answers
318 views

Determine the best subnet mask for the 172.29.0.0 network, with 30 subnets and 1,100 host on each subnet

This was a practice question I found online: Question: You are designing a subnet mask for the 172.29.0.0 network. You want 30 subnets with up to 1100 hosts on each subnet. What subnet mask ...
2
votes
3answers
444 views

What is the effect or purpose of subnet on client PCs?

I understand that the subnet mask when combined with an IP is used to define the range of IPs that the router is responsible for routing. e.g. a router with 192.168.3.1 subnet 255.255.254.0, will ...
2
votes
1answer
1k views

Playing with default subnet mask: understanding the consequences

I'm playing with my router configuration, and I want to understand what happens from changing the default subnet mask from 255.255.255.0 to 255.255.0.0 is expected to do More details, I had Router ...
2
votes
1answer
52 views

Using WLAN Router without creating new subnet

I have the following network configuration at home I'm connected through a NanoStation M5 to the internet. The NanoStation has a DHCP server and provides IP addresses for all wired PCs which are ...
2
votes
2answers
259 views

Why is it improper network design to have two physical NICs, one machine, same subnet, same netmask, same gateway, two different IP addresses?

All I read and can see says to put two different IP addresses on one NIC. I thought if I had two NICs, I'd be better off for speed/throughput. Why is it a wrong topology to have two separate ...
2
votes
2answers
464 views

Cannot reach the computer in WAN

I wanted to split the internet connection in my room. And my brother also wanted a better wifi accessability. So we bought a router (NETGEAR JWNR2010v5). All we wanted works great, good wifi. I have ...
2
votes
1answer
751 views

static IP outside of subnet range

I have two questions, but let me explain the situation first. They are about the (static) IP address of a printer attached to the network. We had this networking setup, using a normal consumer router ...
2
votes
3answers
864 views

Broadcast address in IPV4

I have a small network with the subnet mask 255.255.255.240 and the IP range is 192.168.2.1 - 192.168.2.12. From 192.168.2.1, I want to broadcast a packet. I don't want this packet to go anywhere ...
2
votes
2answers
981 views

Can't connect to Cisco router's settings page

Currently I have a 2 wire modem, and a Netgear WNDR3400. What I want to do is add a Cisco RV100W for its VPN features. Currently the Netgear router is connected to the modem via the WAN port. When I ...
2
votes
1answer
696 views

Routing to one IP via different gateways

I have an OpenVPN connection (point to point). When program connects to server it gets IP and Gateway dynamically, from server. I need to make windows add route to my secure server through given ...
2
votes
1answer
826 views

Two subnets on one switch with no VLAN and possible problems

As far as I know in order to use two subnets on one physical cable VLAN's are recommended. However, is it possible to achieve this (i.e: two subnets on one physical network) like 192.168.1.0/24 and ...
2
votes
1answer
734 views

Creating multiple IP addresses in different subnets on Windows Vista

I am using Windows Vista, and only have 1 NIC. I know that in Linux, I can create IP aliasing such as: eth0 - 192.168.1.1 eth0:1 - 192.168.2.1 eth0:2 - 192.168.3.1 and access all 3 subnets with ...
2
votes
1answer
24 views

On boot, how can I switch to a static IP based on a gateway IP provided by DHCP?

I have a "headless" *NIX host -- let's call it 'foo' -- that is to be accessible via SSH and VNC-tunneled-over-SSH on an arbitrary 192.168.x.y/24 private LAN. Sometimes, I want to physically move ...
2
votes
1answer
23 views

IP subnet /17 for latter range (x.x.128.0 - x.x.255.255)

This site shows 115.93.0.0/17 has the range of 115.93.0.0 - 115.93.127.255 I'd like to setup firewall range of 115.93.128.0 - 115.93.255.255. how can I say it with subnet? my firewall console only ...
2
votes
1answer
294 views

Windows Networking - Treat two subnets as one network

We have an existing (old) network (10.0.0.0/24) and we're trying to add another (new) subnet (20.0.0.0/24) using a Cisco 2901 router. I added the appropriate routes and tested everything out. We're ...
2
votes
1answer
2k views

How many subnets are needed?

I'm just starting out with networks. I'm trying to determine how many subnets are needed for this network: BRANCH1, BRANCH2 and HQ are routers. The Boxes between routers and PCs are switches. The ...
2
votes
1answer
281 views

How do subnetworks communicate with each other? [closed]

I'm a networking newbie and I'm a little bit confused about the difference between the terms: Zone Sub-network Topology I've seen network diagrams where a business's network was divided into three ...
2
votes
1answer
562 views

Separate computers in my apartment can't communicate to each other?

In my apartment, the management provides the building with a network connection. I have my computer plugged into the ethernet coming out of the walls, and my friend who also lives in the apartment ...
2
votes
1answer
59 views

Active directory sites and services

I have 192.168.1.0/23 subnet for wired connection and 192.168.2.0/24 for wireless connection. Do I need to add 192.168.2.0 in AD Sites & services. Right now I have 192.168.1.0/24 added in the ...
2
votes
1answer
224 views

Is there a way to detect a LAN's IP and its subnet mask?

I'm not a English speaker, but I'll try my best make it clear: If your laptop connects to a unknown local network (through a wireless or wired router) and there's no DHCP service at all, and nobody ...
2
votes
0answers
1k views

Accessing a wireless router on a different subnet

Okay, I'll try to describe how this network is set up. I didn't do it personally, but it has been described to me. Firstly, we get our internet from a 3G wireless USB card from ATT. This means that ...
2
votes
3answers
114 views

How come I can ping google but not a PC on a different subnet within my campus network?

I am a newbie to the networking world. I know that one cannot ping two PCs connected to different subnets unless you have a router in between. But, I was wondering how come I can ping www.google.com ...
1
vote
4answers
2k views

Why my subnet mask is not matching with my IP address?

I have a class 'B' IP address 172.16.XXX.XXX in my machine. My Subnet mask is 255.255.255.XXX. I am studying networking now. So until now I didn't care about masking about all. But from Wikipedia I ...
1
vote
2answers
1k views

Do machines connected to the same switch belong to the same subnet?

When we talk about a subnet - do we mean all the systems connected to the same switch? If I have an assigned IP address of 10.0.2.1, am I in the same subnet as that of 10.0.1.39? When we talk about ...
1
vote
2answers
2k views

Isolate two networks in one switch (Cisco SGE2000)

I have a small lab, which has 15 systems for development environment and 5 systems for Testing environment. I have only one Cisco SGE2000 (24-port) Ethernet switch. Currently all on 192.168.3.0/24 ...
1
vote
1answer
7k views

Communication possible between 192.168.0.x and 192.168.1.x?

I have a problem I encounter on a regular basis. I have an access point with a fixed 192.168.0.x IP address. My network is 192.168.1.x. The problem is when I plug the access point into my network, it ...