Experts predict that by 2025 we'll take more than 75 billion connected devices, a number almost triple that recorded in 2019. With networks becoming far more dynamic and complex than ever before, the ability to find IP addresses on the network is essential.

As well, people are connecting to company networks with an ever-increasing number of devices, leading to increased risk non only in security but as well in maintenance and management.

There's too the matter of people connecting to company networks with personal devices. According to Bitglass' 2020 Bring Your Own Device Report, virtually 85% of companies allow their employees to use personal devices on their networks. Security isn't keeping up either, with 63% of respondents saying they were worried about data leakage, 53% concerned well-nigh unauthorized admission to data, and 52% concerned near malware infections.

Fifty-fifty in this environment, network administrators are nevertheless expected to ensure the wellness and security of their network. While information technology's certainly challenging, it'southward not an incommunicable task. It starts with beingness able to find IP addresses on the network effectively.

What is an IP address?

An Internet Protocol (IP) address is a 32-bit number used to identify a device or a network (IPv4 is 32-fleck while IPv6 is 64 bits, but let's focus on IPv4 for now). In its simplest, when you connect to a network, the IP address associated with your device allows you to send and receive data with other devices on that network or across the internet.

Permit's say you desire to access a specific website. The commencement affair you lot'd do is enter a URL into your browser, which queries your domain name server (DNS) to find the IP address associated with that website. This enables your device to find and connect to the relevant website past its IP accost.

IP addresses are in Layer three (the network layer) of the Open up Systems Interconnect (OSI) model. This layer takes care of information routing and transmission from ane network to another. It selects the shortest possible path from i host to another on different networks. It likewise identifies whether the package is destined for the local host, a different host on the local network, or a different network birthday, and in this case it does the necessary routing to the address contained in the frame.

While IP addresses demand to be unique in a network, they are non e'er tied to a specific device. IP addresses tin exist set up manually (chosen a static IP), or tin exist gear up dynamically using a protocol such as DHCP.

The importance of IP addressing in networking

IP addresses let u.s. build complex networks that don't require devices to be straight continued. That's because IP addresses are cleaved into ii components, the network accost and the host address, enabling network engineers to design networks without needing to worry about the specific addresses of every host.

When a network is designed, a network engineer has to ascertain the subnet mask, which decides how many of the available 32-bits will stand for the network address, and how many of the $.25 will represent the host address.

Information technology's like to sending a piece of mail. The mail service office first sorts the mail service based on a zip code (the network), and then as the post gets closer to the destination, it farther sorts the mail based on the street address (the host). Sorting millions of pieces of mail by street accost solitary wouldn't exist scalable, as yous'd have a post role in New York Metropolis sorting mail destined for an address in Los Angeles.

GIF of mail sorting

Source: Deverite

Equally a device is making routing decisions, information technology volition leverage the subnet mask to determine whether an IP accost is in the same network equally the current device, or if it is in a different network.

Classful vs. classless addressing

The topic of network address and host address can be catchy, and warrants a chip more word. To help, permit's commencement with the difference between classful and classless addressing.

Classful addressing

IPv4 addresses consist of two elements: the network address, or network ID, and the host accost, or host ID. Classful addressing splits all available IPv4 addresses into "classes", each course containing a fixed number of accost blocks. Each accost block contains a fixed number of available hosts.

The "class" determines how much of the IP accost' 32-bits are allocated to the network ID: Class A uses 8-bits, Form B 16-bits, and Class C-24 bits.

So what does this mean? Why bother with different types of IP classes? Largely, it comes down to how many individual addresses your network needs. The fewer the bits an engineer allocates to a network prefix, the more individual addresses would be available (simply the fewer the blocks). While Course A may have only 128 blocks available, each of those blocks has over 16.7 meg bachelor IP addresses. In theory, this would have been cracking for big businesses or even unabridged countries, simply some applied limitations use (meet: broadcast domain). On the other hand, in that location are more than 2 meg Form C blocks available, just simply 256 addresses in each.

Example of an IP address table
The main problem of the classful addressing approach was that information technology either leads to wasted addresses (far more than you need), or blocks of addresses that are as well modest. At only 32-bits, IPv4 hit a numerical limitation: at that place just wasn't enough flexibility with the number and size of each address block to serve the hundreds of billions of devices looking to connect to the internet anymore.

Classless addressing

The limitations of this addressing organisation led to the development of the classless approach, or the Classless Inter-Domain Routing (CIDR) system. Classless addressing does abroad with the fixed number and size of address blocks, and allows IPv4 addressing to scale thanks to dynamic network sizing.

Bits customarily allocated to the address's host portion can at present also be used to extend the network component. In essence, classless makes information technology possible to size IP address blocks to the network's specific needs, making classful addressing obsolete.

This can sound complex, so permit'south use an case. A network admin needs to create a network with 300 addresses. Under a classful addressing organisation, they would technically crave a Form B block, equally a Class C block with 8-bits for the host address would only provide 256 addresses – not enough. And while a Class B network with 16-bits for the host address would enable them to have the 300 IP addresses they need, information technology would throw away 65,000+ addresses that would never exist used.

With classless addressing, the network admin can instead set aside 9-$.25 for the host address, leaving 23 bits for the network accost, so that a total of 512 addresses would be available. While information technology is a little more than than the 300 addresses they need, it minimizes waste matter and maximizes the number of network addresses bachelor.

How to assign IP adddresses

IP addresses can be static or dynamic. A static IP address is one that is manually assigned to a device and typically never changes. A dynamic IP address is automatically assigned to a device from a pool of available IP addresses as it connects to a network. Both static IP addresses and dynamic IP addresses take their place in a good network design.

If you're opting for static IP addresses, that means that y'all'll assign each device a specific address that will belong just to it. Information technology won't change with a server update, a router reboot, or anything else. The advantage here is y'all'll always know what device is associated with that specific IP address.

In some cases, static IP addresses can be helpful. If yous want to brand sure that anybody can access a printer, server, or other shared resource at all times from any device, a static IP address is a proficient option.

You'll besides definitely desire to ensure all of your network devices have static IPs.

Static addresses are also a practiced choice if you'll exist using devices that aren't uniform with DHCP, if y'all want to avoid issues a problematic DHCP server can crusade, or if you want amend network security.

However, manually allocating static addresses to each device tin be a massive undertaking if yous have a large network. Y'all also accept to consider invitee devices and how it would deadening everything down if you had to allocate an IP to each i manually. Compatibility issues are likewise probable to arise, so relying solely on static addresses is not appropriate.
To solve this scalability issue, a Dynamic Host Configuration Protocol, or DHCP, automatically allocates IP addresses to devices equally they connect to the network. The advantage here is an administrator doesn't take to oversee the process. The DHCP server can assign a unique IP address, a subnet mask, a gateway address, and other information to every device. It requires less administrative intervention and tin can exist easily scaled.

There are as well potential disadvantages, besides. Since a different IP address tin be allocated to the same device every time information technology connects, connectivity issues that could be resolved by always knowing the IP accost will take longer. You'll want to ensure y'all have solid tracking of IP addresses in your network, or look to leverage a network discovery and documentation tool to automate this process.

The right answer for virtually networks is to use a hybrid system, where near addresses are dynamic, but you take a few static ones for network devices, printers and other critical devices. As you're setting upwards your DHCP server, y'all'll want to ensure that your DHCP address pools do not overlap with any of your static IP addresses – or you'll run into duplicate IP addresses in your network, which can crusade a bit of mayhem!

How to find all IP addresses on a network

Constructive IP address management (or IPAM) starts with knowing how to find them all on your network. Having access to a complete list of IP addresses and the devices they're allocated to can be benign when attempting to resolve connectivity bug.

If you're looking for a specific IP address, the simplest style to detect that device is to use the ICMP ping control. Typing in "ping " with the address you are looking for will let you know whether the device is on the network and responding to pings.

Now, yous can leverage the ARP command, "arp -a" to make up one's mind the MAC accost associated with that IP address.

Just what if you want to detect all the devices on your network?

Starting time, you can leverage the ping command to send out a ping request to a circulate address. For example, if you lot wanted to find all the IPs connected to the 192.168.ane.0/24 network, you tin type:

> ping 192.168.i.255

And then, leveraging the ARP table ("arp -a"), you lot tin can run across all the devices that responded to that ping request. In that location are some limitations to this approach, though, as not all devices reply to pings on the broadcast IP accost.

Another tactic is to only script pings to a specific subnet. For *nix and Mac OSX machines, you can type (replacing 192.168.one with your network):

> for ip in $(seq ane 254); practice ping -c 1 -West 1 192.168.ane.$ip | grep "ttl"; done

On a Windows device, information technology would exist similar to: 

> FOR /L %i IN (1,1,254) DO ping -n 1 192.168.1.%i | find /i "TTL"

In either case, you'll become replies from all devices in that subnet, and tin then leverage the ARP tabular array (control "arp -a") to find their MAC addresses. With this info, you tin can utilize the forward table on your network switch or leverage your network discovery software to pinpoint the specific switch port that the device is continued to — a valuable fleck of info to take.

Continue in mind that this approach is best used for smaller networks or if you're in a existent hurry and demand to do a erstwhile bank check for a detail device. If you lot're looking to discover IP addresses on networks of any substantial size, yous'll want to use an automated discovery tool, like a network scanner.

Why is a network scanner useful?

Attempting to manually rails downwards an IP address on a big network is a challenge. It's practically impossible in corporate networks that accept countless dynamic IP addresses and random devices connecting to them constantly.

This is where a network scanner, or network discovery software, comes in. This blazon of Information technology network management software helps notice all the agile devices on a network, and associates them with their corresponding IP. A network scanner can automatically scan and discover connected devices across all subnets as well.

Network visibility tools like automated network scanners offer a broad range of advantages. Regularly scanning the network allows you lot to identify the devices connected to your network at any fourth dimension, and gather device information such every bit bachelor services, the operating systems in employ, potential risks, and more.

If you're considering adding a network scanner, expect to come across which ones offering network infrastructure mapping as well. The visual context that granular network topology maps provide tin really advance your troubleshooting process.

Regardless of your network's size, if you want to find IP addresses on a network, the virtually efficient approach is to use a dedicated tool. The software will assist reduce your workload and improve efficiency. It will also complimentary you lot upwardly to focus on more important, high-level tasks, rather than spending your time trying to figure out what IP address belongs to which device.

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