A subnetwork, or subnet, is a logically visible subdivision of an IP network. The practice of dividing a single network into two or more networks is called subnetting and the networks created are called subnetworks or subnets.

learn more… | top users | synonyms (2)

-4
votes
1answer
39 views

AWS - What do we mean by associating a subnet with an elastic network interface? [on hold]

I'm trying to understand the meaning of this output: [user@ip-10-1-3-12 ~]$ ip route default via 10.1.3.1 dev eth0 default via 10.1.0.1 dev eth2 metric 10002 10.1.0.0/16 dev eth2 proto kernel ...
236
votes
5answers
48k views

How does IPv4 Subnetting Work?

This is a Canonical Question about IPv4 Subnets. Related: How does IPv6 subnetting work and how does it differ from IPv4 subnetting? How does Subnetting Work, and How do you do it ...
0
votes
0answers
25 views

network inbound from other subnets refused to server A, Server A can go outbound to internal networks, but not internet

I have a RHEL 6 server with 4 NICs on 192.168.2.[30-33]/24 Set with DHCP reservations via infoblox, I have checked and the MACs all match up. ifconfig shows /24 for every netmask, and the routing ...
0
votes
0answers
46 views

Why exactly can't two nearby networks have the same subnet? [closed]

I know it is can't. But after re-think, I don't know the reason why exactly it can't. I did a bit searches, but I couldn't come upon plain answers. Simply say, I have a broadband, giving me IP ...
0
votes
1answer
45 views

Strange behavior on 192.168.6.0 / 24 subnet [closed]

I have a Windows 7 computer running a camera system (Security cameras). The cameras are installed on 192.168.6.0/24 subnet, and I can't get the computer to connect to the 192.168.6.0/24 subnet. I have ...
0
votes
1answer
31 views

incorrent subnet/mask combination

For a network interface, I have defined a range of addresses for DHCP. 3: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UNKNOWN qlen 1000 link/ether 08:00:27:5a:3e:be ...
2
votes
1answer
2k views

Routing between two routers with static routes

I have a Draytek 3200 router and a pfsense rackmount router that I am trying to get to route to each other. I have a subnet on each router and a subnet for the link between, as shown here: As it ...
1
vote
3answers
1k views

multiple subnets on the same cisco switch port

We have several servers on colocation and now trying to re-organize the network by utilizing Cisco ASA 5505 as a router and Cisco 3750x series switch. Network topology is looking like that: ...
1
vote
0answers
71 views

Route two public (ISP assigned) subnets on 'outside' interface of Cisco ASA 5510

We've got a Cisco ASA 5510 that sits on our edge and acts as the PPPoE endpoint for a fibre connection. The fibre connection came with a static IP, which is assigned via PPPoE, and gets picked up by ...
0
votes
2answers
1k views

How to route broadcast packets from machine with two network interfaces on same subnet

I run RHEL 5 and have two NICs on one machine connected to the same subnet: eth0 192.168.100.10 eth1 192.168.100.11 My application needs to receive and transmit UDP packets (both unicast ...
-1
votes
0answers
59 views

3 network interface and 2 subnets (same ip) routing

System description 1 GNU/Linux Box with Arch Linux OS 3 network interfaces 1 for WAN network 2 for every LAN LAN2 and LAN3 description On every LAN we have 3 devices main 192.168.2.2, second ...
0
votes
0answers
64 views

Best way to divide network?

I own a small company that recently is outgrowing our current network. Currently we have a 10.216.170.0/24 network and therefore only a limited number of available IP adresses. Now, we have a single ...
-1
votes
2answers
48 views

What is this router's IP address(es)? [closed]

What is the IP address(es) of the router in my picture? In my picture, you can see that I have question marks next to the router's interfaces, because I'm not sure if those are right. Can someone ...
1
vote
0answers
51 views

Route public subnet to client location

Due to the fact that my ISP introduced CGN/DSLite and I still need public IPv4 addresses, I was thinking about tunneling an unused /29 that I own from my server to my local Linux box. After doing ...
2
votes
4answers
14k views

Subnet calculator for MS Excel

I quite often use the handy subnet calculator here: http://www.subnet-calculator.com/ Which I find very useful. However, does anyone have details/a link for a version of this that offers similar ...
1
vote
1answer
78 views

Why do I lose network connectivity for a virtual machine outside /24?

I have a bunch of virtual machines (Ubuntu Server 14.04) hosted on a single real server (Ubuntu Server 14.04 with KVM). The number of virtual machines grow, and I'll soon have more than 254 of them. ...
0
votes
1answer
100 views

adding a third subnet on the same router

cisco 2800 series (isp cross connect)Eth0/0 192.x.x.x 255.255.255.252, Eth0/1 192.x.x.x 255.255.255.224 ##Eth0/1.1 192.x.x.x 255.255.255.128 <--- want to add this block in!## I've been granted ...
-1
votes
1answer
46 views

Merge three DNS Servers into one [closed]

The situation is as follows: Currently three DNS servers are separated from each other, these are to be merged into one. The goal is to have only one DNS server that handles all requests of the three ...
0
votes
0answers
26 views

OWPING communicating between tcp and tcp6

I am trying to deploy the perfSonar toolkit on my network. I'm testing the one-way ping tool on a local subnet, which contains the monitoring station (in this case, a laptop) and a host ( a cubox-i ...
14
votes
5answers
1k views

Are Cisco admins expected to understand classful networks?

While studying for the CCENT exam, my reference materials have made an alarming number of references to class A/B/C networks. Thankfully they just treat Class A/B/C as shorthand for /8, /16, and /24 ...
1
vote
2answers
43 views

Clients on Local Network — simple test?

I am developing a web system for my school (it's in PHP, but that's not important). The system needs to have different behaviors depending on whether or not the user is on the school network ...
0
votes
2answers
655 views

Reverse Proxy multi-subnets

I'm having some problems that I think I should not be ordinarily facing. But after being beating senseless by this, I'm calling out uncle. I have previously posted something along these lines here: ...
2
votes
2answers
79 views

How to get a report of all mac addresses on another subnet?

We have an MPLS consisting of two branches: Location1 and Location2. I am using the Softperfect netscan to report all ip addresses and mac addresses of devices on Location1 where my workstation is ...
2
votes
1answer
37 views

Sonicwall Fake network

I have a Sonicwall NSA 3500. My LAN is 192.168.0.0/16 with my Sonicwall at 192.168.11.251 I have a new device that I need to connect, it has 2 NIC cards one communicates with the network, the other ...
0
votes
3answers
5k views

How to reach a device on a different subnet?

I have what may seem to be a basic question about routing, but I ask it because I am not sure where to start. I have a simple network setup: Client1, Win7, 192.168.0.50, default gateway is set as ...
0
votes
2answers
56 views

what happens when a DC fails? How can the clients identify DC failure? [closed]

When a DC fails, it loses the privilege to authenticate and so client will find for secondary DC closest to its site. In another scenario, client has selected a DC closest to its site by using subnet ...
-2
votes
1answer
39 views

Can a site contain domain controllers from multiple domains?

For e.g. I am creating a site with 2 clients and 1 DC in it. I am setting the subnet to cover these objects. So my site say SITE1 will have 2 clients and 1 DC. So when one of these clients tries to ...
0
votes
2answers
89 views

VMware vSphere as gateway to internal network

I'm looking for info if it's possible for vSphere to act as gateway from my external network to an internal network. Basically: The vSphere host is on a 10.0.0.0/24 which is my "external" network. ...
1
vote
1answer
214 views

Routing between 2 different subnets on 2 different interfaces in SonicOS

I'm having a bit of a problem allowing traffic between two of my subnets. Here's the structure I've built. The X0 interface has our windows server on it and it handles DHCP/DNS, etc. X1 has the WAN ...
1
vote
2answers
223 views

How can I use a gateway on another subnet?

I'm trying my first attempts at routing and hitting the "Network is unreachable" message. My goal is to successfully ping frome one machine (subnet 10.56.34.0) to a machine on a completely ...
0
votes
1answer
37 views

VLSM subnetting (CCNA 4) [duplicate]

I do not understand the answer to this question: I thought it was like this: /24 = 126 hosts /23 = 254 hosts /22 = 510 hosts /21 = 1022 hosts Branch 4 has 850 hosts, am I missing something?? Thanks ...
1
vote
1answer
45 views

Is there a way to use Bind9 $GENERATE directive for rDNS of ranges bigger than /24?

The $GENERATE directive of bind9 makes it possible to autogenerate the reverse mapping for a range of IPs what is really helpfull for reverse dns of a dhcp range. But it seems that the $GENERATE ...
0
votes
0answers
44 views

OpenVPN identical subnets for client & server

I have an OpenVPN server (Ubuntu 14.04 routed mode) on a local network with a subnet of 192.168.0.0/24. The subnet it uses is obviously a very common subnet. My problem When a client is out and ...
0
votes
1answer
71 views

Making a reverse zone file on a 255.0.0.0 subnet

I’m trying to setup a reverse zone file for this subnet that has two hosts on it: 10.10.100.10 and 10.128.5.10. This means he netmask for the subnet would be 255.0.0.0. I inferred that the file name ...
0
votes
3answers
439 views

Routing between two subnets using a Linux box with two NICs

I have a Linux box with two NICs, each connected to a different LAN: Network A: 192.168.1.0 255.255.255.0 Network B: 192.168.2.0 255.255.255.0 The routers are: 192.168.1.1 192.168.2.1 Linux NICs are ...
-4
votes
1answer
44 views

Sonicwall 240, different subnets [closed]

I have sonicwall 240 for now x0: Lan 192.168.25.1 x1: Wan my internet connection x2: DMZ 192.168.102.1 I want to add x3 as new subnet with this address 170.20.120.1 what should I do? ...
-1
votes
1answer
83 views

Some computers in my subnet do not recognize names of other pc's

I have two subnets: 192.168.0.1-255 192.168.50.1-255 Ewerything works via VPN (because physically computer from both subnets are in different locations). We also have active directory. Now, the ...
0
votes
3answers
89 views

Can I create VLANs when there are subnets already?

I need to have separate subnets in each room but at the same time, I need a few computers (spread across rooms in different subnets) to be in a single VLAN. Is it possible or do I need to rework the ...
2
votes
1answer
184 views

Openvpn different subnet with dynamic ip using client-config-dir (cdd)

Good Morning, I need some help for a specific configuration in a server. Let's say I have two kind of people that will connect to my VPN. Pepole from Group A and people from Group B. I need them to ...
12
votes
8answers
9k views

What is the network address (x.x.x.0) used for? [duplicate]

It appears to be common practice to not use the first address in a subnet, that is the IP 192.168.0.0/24, or a more exotic example would be 172.20.20.64/29. The ipcalc tool I frequently use follows ...
0
votes
1answer
39 views

Delegate NS resource record of IPv4 subnet

Is it possible for a reverse zone to name another DNS server in the NS record? I want to delegate DNS for all addresses within a subnet to a site using that subnet. Our office leases a subnet which is ...
2
votes
3answers
180 views

DHCP Relay vs Multi-Homed DHCP Server

I'm sketching out a new network topology and I'm unsure of how to solve the issue of DHCP between two VLANs. 10.50.2.0/23 will hold the majority of our users, corporate wifi, printers etc. ...
0
votes
1answer
61 views

Set up Wheezy Subnets

I'm trying to create multiple subnets on a Wheezy server, where I can run multiple virtual machines off of each subnet. Initially, I'd like to create 2 and I've gotten one of the subnets working, but ...
-4
votes
2answers
175 views

Exercise regarding public IP address and its “class C” [closed]

An exercise I am doing asks the following:- Identify what your public IP address is. Using public information sources, see what you can learn about your IP. If you don'ʹt find anything on your ...
0
votes
1answer
80 views

What are the disadvantages of re-using the same IP scope in multiple subnets? [closed]

We're designing a somewhat large system that we're not really qualified to design. It will be something like a campus: one main, large network, with about 20 sub-networks that are like departments ...
0
votes
2answers
118 views

2 WAN with separate routers, but need to be same network

My office has a 100mbps fibre internet and we connect all devices to it via a Netgear WNR3500L. I am thinking of subscribing to another 200mbps with another ISP (because the current ISP does not have ...
0
votes
1answer
44 views

cisco firewall access rules for intra-subnet traffic

I have a Cisco 5505 in our office, and everything is on the 10.0.1.0 network. We have a cheap wireless router that we would like to use. The router is sitting behind the inside interface, and is ...
0
votes
1answer
216 views

XenServer - VMs to access Internet, but should not be visible from the Internet

I have installed XenServer on my server at the Hetzner datacenter. I have bought an additional /29 subnet containing 6 usable IP addresses from them. I want to install more than 10 VMs on this ...
0
votes
0answers
248 views

XenServer 6.2 - Hetzner host - Additional Subnet Configuration

I have a dedicated server on Hetzner, on which I have installed XenServer 6.2 . The server comes with one public IP address. I purchased an additional subnet containing 6 usable IP addresses, for use ...
1
vote
1answer
119 views

Netgear XSM7224S / DLink 1210-48 Static Lag (Trunk Failure)!

I need to configure a Netgear Switch(XSM7224S) and DLink Switch (DL1210-48) with two trunk ports. I did the same and created a lag (static) between them, afterwhcih a reboot was performed on both of ...