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

learn more… | top users | synonyms

22
votes
5answers
46k 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 ...
19
votes
8answers
11k 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 ...
11
votes
7answers
7k 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
4answers
590 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 ...
8
votes
5answers
4k 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 . . . . . . . . . ...
7
votes
1answer
2k 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
24k 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
votes
2answers
4k 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
3k 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
2answers
3k 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
6k 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 ...
3
votes
5answers
2k 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 ...
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
1k 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
3answers
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.
3
votes
2answers
558 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
1answer
161 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
1answer
320 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 ...
2
votes
5answers
6k 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
971 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 ...
2
votes
2answers
487 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
57 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
2answers
674 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
3answers
212 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
893 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
3answers
164 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
277 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
543 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
580 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
563 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
229 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
188 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
489 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
196 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 ...
1
vote
2answers
955 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
783 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
466 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 ...
1
vote
1answer
168 views

Regarding IP subnetting process

Professor taught the following scenario. An organization has purchased a Class-C address 216.21.5.0 and would like to use it to address its offices at Arizona, Florida and California. It has the ...
1
vote
3answers
267 views

Network addressing without wasting IP addresses

I know how to do the classic "network addressing" when I am allowed to waste IP addresses. For example, if I need to hook up 9 computers, I could use a /28 subnet, which allows 16 hosts to be mapped ...
1
vote
2answers
304 views

How to find the network address of a given subnet?

How do I find the x th subnet of X.X.X.X /XX (300 th subnet of 172.16.0.0 /29)?
1
vote
2answers
1k views

Ping a PC connected through crossover cable to one connected to router

I want to ping (technically, i need to connect to port 80) a PC that is connected to a second PC (through crossover cable), that's connected to a Router. I have a little sketch of what I'm trying to ...
1
vote
2answers
415 views

What is subnetting?

What are the subnet mask, first available host address of subnet one (NOT subnet zero), and the maximum number of hosts per subnet for the network below? (You need to allow for maximum number of ...
1
vote
2answers
593 views

Setting up the subnet mask for two separate connections on XP?

I'm on Windows XP SP3 and basically my topology consists of 3 computers (see drawing for more detail), a wireless connection to the Internet and a wired connection to a router. My main computer (A) is ...
1
vote
1answer
380 views

Can a subnet has more than one gateway?

I am new to networking while reading Network+ Guide Networks books, I came into Subnets but, nowhere they mentioned how many gateways a subnet can have. For example for 192.168.1.0/24 the gateway is ...
1
vote
2answers
4k views

How should I reserve IP addresses for my home LAN?

My Netgear router supports MAC-based IP reservation, and I'm setting up my very first home LAN where I want multiple Ubuntu servers to be given dedicated IP addresses. This is a consumer-grade router, ...
1
vote
2answers
225 views

Viewing computers connected to my ISP

If there are many computers connected to my ISP then doesn't that mean they are all on the same network? If so, I should be able to see them. Why is it that this does not happen? The question Other ...
1
vote
2answers
92 views

Why nic with incorrect subnet mask can still ping the gate way?

At first, my network config was like this: $ ip a 2: em1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000 link/ether 3c:97:0e:bd:b1:68 brd ff:ff:ff:ff:ff:ff ...
1
vote
1answer
226 views

What is major network mask and subnet mask

I've been served with a question to find Major Network Mask and I've only given Host IP address and sub-net mask. I have to find the Major Network Mask using Host IP and sub-net mask. Another ...
1
vote
1answer
546 views

How to find CIDR subnet for a public Internet IP address?

Usually I do not worry about subnet of an IP address on the public Internet, but after I began using Amazon EC2 firewall, it got me thinking. EC2 firewall configuration requires an IP to be written ...
1
vote
2answers
1k views

Two hosts on same subnet can't see each other

I've got two routers with two separate public IP addresses on the same subnet, but I can't get them to talk to each other. Both are connected to the internet (ISP-provided gateway) via Ethernet ports ...