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.

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Connectivity issues with dual NIC machine in EC2

I'm trying to get some servers set up in EC2 in a Virtual Private Cloud. To do this, I have two subnets: 10.0.42.0/24 - Public subnet 10.0.83.0/24 - Private subnet To bridge these two, I have a ...
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1answer
28 views

Trying to understand the flow of packets going from one VLAN to another

I am trying to understand the flow of the packets from one computer to the other in the same VLAN but on a different subnet as explained here. And a case shown is: Suppose the same sending ...
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10answers
6k views

Use first or last free IP for the default gateway?

Please assume a simple LAN on 192.168.100.0/24. Would you configure the default router on 192.168.100.1 or 192.168.100.254 and why? Thanks
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3answers
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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 ...
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2answers
56 views

Setting up a server with two NICs using two separate subnets (each on a different VLAN)

I'm using Ubuntu 14.04 (standard server install + OpenSSH, biosdevname=0 during instal to keep the network names simple) in an environment where I have two non-overlapping subnets M and N on different ...
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2answers
860 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 ...
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1answer
49 views

Are smaller subnets more efficient (when routing to/from)?

Say I have 4 IPs in a subnet. Scenario 1 (/24): Client A: 10.0.0.1/24 Client B: 10.0.0.2/24 Client C: 10.0.0.3/24 Client D: 10.0.0.4/24 Scenario 2 (/16): Client A: 10.0.1.1/16 Client B: ...
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1answer
31 views

How can I enable outgoing HTTP/HTTPS requests on an EC2 in a public subnet within a VPC on Amazon AWS

I set up a VPC using scenario 2 from the AWS Docs: http://docs.aws.amazon.com/AmazonVPC/latest/UserGuide/VPC_Scenario2.html I've assigned an Elastic IP to an EC2 instance running in a Public Subnet. ...
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0answers
34 views

Problem with v6 subnet routing

I have a freebsd machine connecting to my sixxs ayiya-tunnel. As I decided to implement IPv6 in our complete network and not only one interface I got myself a routed /48 from sixxs. I'll use ...
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1answer
369 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 ...
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1answer
3k 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 ...
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1answer
35 views

Is it Possible to Capture All HTTP Packets to a Target IP on a subnet?

I've been trying to use tcpdump to capture packets to a target IP on my subnet, but am unable to do so successfully. I've tried: tcpdump -i eth0 net network-ip-address/27 -A and tcp port 80 But it ...
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1answer
47 views

Changing Network Subnet Limited User Access

Our network was originally running a 192.168.3.1 /24 network with 192.168.3.1 being the gateway on a pfSense box. We decided to increase our IP range by changing the network to a 192.168.3.1 /23 ...
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1answer
15 views

Adding static routes to remote networks

Having: My local machine (A) A remote router (B) who knows a remote network/subnet (X) My local machine's is located at the default router's (C) subnet, who know the remote router (B), but has no ...
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1answer
65 views

Network Clients receiving DHCP responses from wrong subnet

This is my first time posting and I have searched for similar question to the best of my abilities yet believe none to be helpful for my cause. My problem is, that I have a Fritz.Box 3270 as router, ...
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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 ...
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0answers
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subnetting of 16.0.0.0 into 2000 subnets [duplicate]

I got this question and the teacher rejected my answer but didn't tell me why. Question: An organisation is granted the block 16.0.0.0. The admin wants to create 2000 subnets. A. Find subnet mask ...
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0answers
30 views

Deny access from from/to subnet

We are running a VPC on Amazon. Our main network is 192.168.0.0/16 We have a subnet at 192.168.1.0/24 Two subnets which are entrypoints for our VPNs at 192.168.2.0/24 and 192.168.3.0/24 And more ...
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2answers
757 views

MAC OS X Server Lion - how to join two subnets?

I've got two routers connected to two different providers. I also have Mac OS X Lion server connected to both of them, so it looks like this: [INTERNET] [INTERNET] | ...
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1answer
22 views

Switching network from netmask 24 to 22

I currently have a firewall set up as x.x.1.1 and a secondary of x.x.2.1 on the firewall. On the DHCP server I have a superscope with 2 scopes handing out DHCP addresses. I was told it would be best ...
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1answer
43 views

private network with single IP multiple servers [closed]

I am trying to set up a subnet in our company. We got several (10+) Linux servers for computing but we can only get 1 static IP (company policy, 10.x.x.x address). So the idea is to place a routing ...
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2answers
15k views

Multiple VLANs, multiple subnets, single DHCP server?

At my job we are prepping to transition from multiple LANs connected over slow VPN connections to a single MAN connected over fiber, and I've got a few questions. First of all, we are planning on ...
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1answer
94 views

Adding subnet to a vsphere with single vcenter and esxi host

Let me start of by saying that I do not specialize in networking, I am in the process of adding additional VMs to a testing environment and wanted some recommendations. In this case I am running a ...
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1answer
49 views

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

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 ...
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5answers
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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 ...
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0answers
35 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 ...
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1answer
57 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
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1answer
39 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 ...
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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: ...
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322 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 ...
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0answers
71 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 ...
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2answers
52 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 ...
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0answers
54 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
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4answers
15k 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 ...
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1answer
108 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
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1answer
104 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 ...
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1answer
58 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
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0answers
35 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 ...
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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 ...
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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 ...
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2answers
679 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: ...
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2answers
104 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
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1answer
44 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 ...
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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 ...
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2answers
67 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 ...
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1answer
44 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 ...
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2answers
113 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. ...
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1answer
525 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 ...
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1answer
54 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 ...
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1answer
61 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 ...