Questions tagged [subnet]
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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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 by ...
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How does IPv6 subnetting work and how does it differ from IPv4 subnetting?
This is a Canonical Question about IPv6 Subnetting.
Related:
How does IPv4 Subnetting Work?
I know a lot about IPv4 Subnetting, and as I prepare to (deploy|work on) an IPv6 network I ...
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Is X.Y.Z.0 a valid IP address?
Are IP addresses with a 0 in the last octet valid?
10.6.43.0
In my case, I have the the following netmask
255.255.252.0
What about a 0 for the other octets?
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CIDR for Dummies
I understand what CIDR is, and what it is used for, but I still can't figure out how to calculate it in my head. Can someone give a "for dummies" type explanation with examples?
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Connecting to a remote server through a VPN when the local network subnet address conflicts with a remote network
This is a Canonical Question about solving IPv4 subnet conflicts between a VPN client's local network and one across the VPN link from it.
After connecting to a remote location via OpenVPN, clients ...
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What are the implications of having two subnets on the same switch?
Can anyone tell me what some of the implications of having two different subnets on the same switch would be if VLANs are not being used?
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Is it better to use the 192.168.x.x or 10.x.x.x address range for a small business network?
For best performance and ease of management, is it better to use 192.168.x.x or 10.x.x.x range of addresses for a small (<50 PCs) business network?
This would correspond to a subnet of 255.255.0.0 ...
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IPv6 subnetting a /64 - what will break, and how to work around it?
In IPv6, you are not supposed to subnet to anything smaller than a /64 (RFC 5375). Among other things, SLAAC does not work with smaller subnets, and apparently also some other features will break.
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When/why to start subnetting a network?
Under what conditions does one start to consider subnetting a network?
I'm looking for a few general rules of thumb, or triggers based on measurable metrics that make subnetting something that should ...
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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 ...
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tcpdump filter on network and subnet mask
I'm using the following tcpdump command:
tcpdump -w net75.out -s 0 host 65.207.95.222
I want to change the filter on the single host to be all addresses in the following subnet:
65.192.0.0/10
I ...
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Linux Command line tool to work with netmasks / CIDR notation [closed]
I'm terrible at working out network subnets in my head. Is there some command line tool for linux (ubuntu packages a plus), that lets me put in 255.255.255.224 and it'll tell me that is a /27?
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What is the difference between 0.0.0.0/0 and 0.0.0.0/1?
In the history, I mostly used 0.0.0.0/0 for "match every IP address". Recently, I saw a 0.0.0.0/1 subnet filter.
What is the difference between 0.0.0.0/0 and 0.0.0.0/1 and what's the ...
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Customer site is out of IP addresses, they want to go from /24 to /12 netmask... Bad idea?
One of my client sites called to ask me to change the subnet masks of the Linux servers I manage there while they re-IP/change the netmask of their network based on a 10.0.0.x scheme.
"Can you change ...
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Is it possible to SSH access a server with a misconfigured subnet?
We have a server where one of our engineers misconfigured the subnet and now we are locked out of this server and the only access that I know of would work is a serial console from IDC (it means ...
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multiple physical interfaces with IPs on the same subnet
I have a linux box with 9 NICs on it, and I want eight of them to have unique addresses on the same subnet, e.g.:
ifconfig eth1 192.168.123.1 netmask 255.255.0.0
ifconfig eth2 192.168.123.2 netmask ...
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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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How to work out how many IP's you've got available on a /29 network mask [duplicate]
This might sound like a stupid question but I would really like to know how I would work out how many IP's I've got available on this network range:
196.44.198.32/29
Can someone explain it to me, ...
user21021
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Best way to segment traffic, VLAN or subnet?
We have a medium-sized network of around 200 nodes and are currently in the process of replacing old daisy-chained switches with stack-able or chassis style switches.
Right now, our network is broken ...
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Does a Gateway of a Subnet need to be a "real" Computer?
Is a Gateway always a real computer or just a "logic" entity, which can be on any address, except the broadcast IP?
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AWS: NAT Gateway in public subnet. Why?
As I understand it, a public subnet is one that can route traffic to the internet via an Internet Gateway, and a private subnet is one that cannot (can't reach the internet nor it can be reached from ...
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Are same IP address with different submask unique? [duplicate]
Possible Duplicate:
How does Subnetting Work?
In a same block of IPv4 addresses, can there be same IPs with different submasks?
For example, can I have this:
180.70.65.140/26
180.70.65.140/25
...
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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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How do you choose your IP addressing?
In the life of a system administrator, always will come a moment when an IP subnet needs to be defined. Be it your small home LAN or the endless company WAN where madness lurks in the depths of ...
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I am able to ping a device on a different subnet without passing through a L3 device. How?
I have two devices in the same broadcast domain. My PC and an Avaya IP Control Unit.
My IP is 10.168.10.154/22.
Avaya Device IP is 192.168.10.99/23.
I am able to ping this device and don't ...
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How to add subnets to Windows Firewall "local subnets"?
On Windows Firewall under an individual rule the scope tab allows you to define which ips are subject to the rule. One of the built in options is "Local subnet".
How can you add an additional subnet ...
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Creative IP/subnet/dns schemes
I've only administered rather small networks (<=25 nodes). Usually I put the gateway .1, dns/proxy as .10, mail at .20, printers at .30-39 and so on and so forth. I never directly use IP addresses ...
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A website hosted on the 1.0.0.0/8 subnet, somewhere on the Internet?
Background
I'm attempting to demonstrate, using a real-world example, of why someone would not want to configure their internal network on the 1.0.0.0/8 subnet. Obviously it's because this is not ...
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How to pick AWS CIDR within the CIDR ranges of VPC?
When i try to add a new subnet in my VPC I get this message:
172.22.128.0/24 CIDR is not within the CIDR ranges of VPC.
My current VPC CIDR is 172.22.130.0/28
Any help?
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Blocking or rate-limiting IPv6: what size prefix
Given that blocking a single IPv6 address would seem to be somewhat pointless as an end user typically has at least 2**64 of them, we need to block a range, which identifies a "site".
A &...
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Can I subnet a subnet?
Apologies in advance for the botched terminology. I have read the Server Fault Subnet Wiki but this is more of an ISP question.
I currently have a /27 block of public IPs. I use give my router the ...
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Why does this allocation of client static IP in OpenVPN fail?
I am running an OpenVPN server, and I want to assign a specific client a static IP.
This is my server.conf. I think this configures the pool of virtual IPs to span from 10.5.24.209 to 10.5.24.223.
...
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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
Thomas
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Is there such a thing as too many IP addresses?
We've started a small debate in the office, and I've hit the point where I no longer have the technical knowledge to continue.
Is there such a thing as having too many IP addresses? I'm not ...
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How does VLAN subnetting work on IPv6?
I have a network with about dozen VLANs, most with inter-VLAN routing, some without. They might talk to each other but not to the other's gateway. It's not divided because of security or congestion, ...
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Bonjour/mDNS Broadcast across subnets
I have just setup a new OSX Server in our office and verified that everything is working fine over our wired network (192.168.126.0/24).
The problem that I am having is that our clients (Mac Laptops) ...
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What are the implications of expanding an internal subnet mask?
Our network is currently working on a 192.168.0.x subnet, all controlled through DHCP, except for the few main servers who have hard-configured IP address settings.
What would I kill if I changed the ...
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DHCP Server with multiple network interfaces and different subnets
I am trying to set up a dhcp server (isc dhcpd on debian 8 (vm inside an esxi environment)) with 4 network interfaces, eth0-3. The dhcp server should serve a different subnet on the interfaces eth1, ...
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connect two routers with different subnet
I've seen a lot of questions about this, but haven't really understood/didn't match my issue.
I'm a newbie regarding networking.
I got two routers, both are connecting to the wan (giving them ...
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Openvpn for client/server in same subnet
I'm trying to openvpn into an office network (192.168.1.0/24) from a client sitting on a network with the same subnet (also 192.168.1.0/24). It is a linux (ubuntu 9.10) server and windows client.
I ...
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When to use routable vs non-routable IP addresses [closed]
As I understand it, there are several "non-routable" IP ranges:
class A reserved space 10.0.0.0/8
class B reserved space 172.16.0.0/12
class C reserved space 192.168.0.0/16
class E reserved for ...
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Running out of IP addresses
We are running out of IP addresses on our expanding network. The current range is 192.168.1.0/24.
Considerations:
We use an ISA server as a proxy for all web traffic, this is our current default ...
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Maximum Number of Hosts per Network
I recall reading this in some (I think) Cisco documentation years ago, but can't find it or any other reference to this recommendation.
Anyone know what I'm talking about? Anyone still follow these ...
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Networking Question - What is a VALID Subnet Address? [duplicate]
Possible Duplicate:
How does IPv4 Subnetting Work?
I am currently revising Networking for the Cisco CCNA1. One of the questions that I am struggling to answer is the following:
Which of the ...
Phil
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Linux : Ping all the host in the subnet
There is one solaris command to ping all the hosts in the subnet by issuing :
ping -s 255.255.255.255
Is there anything similar to this one in linux ? My intention is to find one mac address as ...
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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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If I change a router's subnet mask to one that includes the old one, will the hosts with the old configuration still work?
Currently I have a router that is addressed as 10.2.1.1 on a 10.2.1.0/24 network. All of my hosts have default gateway 10.2.1.1 with mask 255.255.255.0.
I want to know: if I change my router to 10.2....
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How can we explain CIDR notation with /24 and /32 to a manager? [closed]
Update: I seem to get two kinds of answers and I need to get more clarity on how they relate (or not). What we have so far is, roughly in the lines of:
you have 32 bits, the / indicates how you split ...
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Changing netmask from /24 to /16 on a Windows 2003 domain
I have a Windows 2003 domain using 192.168.0.0/24 with all static addresses (no dhcp). I want to move to 192.168.0.0/16 because we need more addresses. I understand that we need to change netmask ...
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Best Approach for subnetting/VLANing traffic?
Our network is currently setup with no subnets or VLANs. We are looking at going to VoIP so this needs to change before VoIP is installed. I believe that we want to use VLANs to separate Voice and ...
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