What Is IP? [A Beginner’s Guide]

Imagine you want to send a letter to a friend living abroad. You’ll need his address so that the postal service can deliver it.

Likewise, your computer needs to know the location of a website on the internet or a computer on a network to contact it.

This is where the IP address (often called only IP) comes into the picture.

So what is IP exactly?

It is a unique numeric identifier for machines in a network.

In plain English, this means an IP address tells the exact location of a website on the internet or a computer in a network.

However, it is just one of the many things that devices need to talk to each other.

Think about it this way:

Even if you know your friend’s address, you wouldn’t be able to reach him if there’s no postal service between you two.

Similarly, without a standardized and robust mechanism, your computer cannot talk to a website on the internet.  

So what is this mechanism?

Well, it goes by the name of TCP/IP (also known as the Internet Protocol Suite).

Let’s find out what it is all about.

TCP/IP – A Brief Explanation

TCP/IP is a communication protocol that powers the internet.  In simple words, it allows computers to speak with each other via the Internet.

As the name suggests, TCP/IP has two parts or layers — TCP and IP.

What Is TCP?

TCP, which stands for Transmission Control Protocol, is the upper layer.

It has two main functions:

One, it breaks information into smaller chunks, called data packets or simply packets.

Two, it sends data packets on their way.

Where to?

To another identical TCP/IP protocol suite at the destination site.

Data packets are not sent in any particular order or through a specific route. Instead, they are routed along the fastest network channels randomly.

So, once data packets reach their destination, it is the job of the receiving TCP/IP protocol suite to collate data correctly.

Now that we know what TCP does, let’s find out how IP helps.

What Is IP?

IP, aka Internet Protocol, forms the lower layer of the Internet Protocol suite.

It has the all-important job of tagging each data packet with information regarding its source and destination.

This is important. If the internet address of the destination is missing, a data packet will not be delivered.

You see, a data packet doesn’t travel straight to its destination. Instead, it passes through multiple in-between stations, called gateways. (They constitute the network nodes that create the global Web, but that's a story for another time.)

At each gateway, a networking device checks the shipping address and then forwards the packet to the right direction.

In a nutshell, TCP takes care of how data is packetized — while IP ensures these packets reach their correct destination.

TCP/IP Model Layers

TCP/IP has the following four layers.

The Application Layer

It ensures communication between applications connected to a network. One such application is the web browser through which you are reading the current article.

Its protocols include:

• Hypertext Transfer Protocol (HTTP) - It is the underlying protocol used by the World Wide Web. It defines how files are transferred on the internet.
• File Transfer Protocol (FTP) - A standard network protocol, FTP is used for transferring files between a host and server on a network.
• Post Office Protocol 3  (POP3) - It is the standard protocol used for retrieving emails from a mail server.
• Simple Mail Transfer Protocol (SMTP) - Mail servers use this protocol to transmit email over the internet.

The Transport Layer

Its main function is to resolve all host-to-host communication. Its protocols include TCP (Transmission Control Protocol) and UDP (User Datagram Protocol). These two protocols carry practically all internet traffic.

However, the two operate in a different manner. TCP is the slower of the two as it ensures the connection between parties is stable and reliable, and that all data packages are delivered. Web servers utilize TCP to fulfill user request and load a site.

UDP - User Datagram Protocol - is not nearly as reliable as TCP, but it has its uses too. Video stream services deploy it heavily, and so do voice-over-IP telephony where a small drop in connection results is (hopefully) minor visual or audio blurring but doesn't really ruin the experience.

The Internet Layer

Also called the network layer, it logically transmits data packets over the internet. Some of the internet layer protocols are IP (Internet Protocol) and ICMP (Internet Control Message Protocol).

The IP fulfills its task by encapsulating the transmitted data packets with logically structured information that allows network devices to determine where the packet comes from and where it is supposed to go. Thanks to the IP, the receiving device can also put the received data packages in the right order.

The Physical Layer

There is no mystery here, the name says it all: the physical layer transmits data in the most basic of forms, namely electric pulses. Essentially, it is the hardware that carries network signals. This includes network cards, cables, routers, and so forth.

Now, let’s check out the two versions of IP — IPv4 and IPv6.

IPv4 and IPv6 in Simple Words

IPv4 came much before IPv6 and still carries about 75% of the traffic, first let’s look at that one.

Understanding IPv4 and Its Shortcomings

Released in 1981, IPv4 is the original internet addressing system.

It follows 32 bits, so the IP address format, in this case, is four numbers, ranging from 0 to 255 and separated by a period.

Here’s an example: 192. 12. 30.1

In total, there are approximately 4.3 billion IP4 addresses.

That said, many IP addresses are reserved for special purposes.

Therefore, the actual number of IPv4 addresses that can be used on the internet is much less — about 3.7 billion.

And therein lies the rub.

3.7 billion IP addresses seemed more than enough in 1981— but, guess what, things have panned out differently.

We ran out of IP4 addresses in 2018, according to a report.

In case you’re now thinking, “Oh shit! What we’re gonna do?”, it’s gonna be OK.  

IPv6 is here, and it is virtually limitless (but more on that later).

Besides being insufficient, IP4 has another major drawback — security.

IPv4 was never designed for security, since at that time no one had anticipated the current network security threats.

Today, the standard framework used for secure connections between two points is Internet Protocol security or IPSec. It works by authenticating and encrypting data sent over an IP network.

The problem with IPv4 is that IPSec doesn’t come built-in — but is optional.

Given the recent rise in cybercrime, the lack of built-in security makes it harder to deal with an increasingly hostile environment on the internet.

Another problem with IPv4 is related to its configuration. It must be configured manually or through the Dynamic Host Configuration Protocol (DHCP).

Also, its headers are relatively complex and slow to decode, which translates into less efficient packet processing.  

Understanding IPv6 and Its Advantages

IPv6 — aka Internet Protocol version 6 — is the new kid on the block. And it is here to stay a long time.

Unlike IPv4, it uses 128-bit internet addresses.

In simple English, this means it can support 340 trillion-trillion-trillion IP addresses. That’s 12 zeros after 340!

However, quantity is not the only advantage IPv6 enjoys over its predecessor. It is also more secure, as IPSec comes built in.

Also, address auto-configuration is baked into it, which means the device does the address allocation by itself.

Lastly, IPv6 header is much simpler and hence easier to process.

Coming back to IPv4, did you know there are five classes of IP addresses? Or that only three classes are for public use?

Well, let’s find out more about this.

Classes of IP Addresses

IPv4 has five classes of IP addresses: A, B, C, D, and E.

However, only IP addresses from classes A, B, and C can host actually useful IP addresses.

This is because:

Class D is reserved for multicasting and class E for experimental purposes.

This system of IP address classes was introduced to simplify assigning of internet IP addresses, and the classes were based on the size of the network.

For instance, Class A was created for a small number of networks having numerous hosts.

In contrast, Class C was developed for a large number of networks with a small number of hosts.

Each of these IP address classes allows for a range of valid IP addresses.

And it is the value of the first octet (the first decimal number) that determines the class — as the following table shows.

Note: In reality, some of these IP addresses are marked as private addresses.

Understanding the Network and Host Part of an IP address

Every IP number comprises of two segments: network part and host part.

As is the case with most things technological, names are quite descriptive. The network part identifies networks, while the host part specifies the number of supported hosts.

In a Class A address, the first decimal number is the network portion, while the rest are the host portion. Consider these two IP addresses: 10.30.110.1 and 10.2.11.9. By looking at them, we can easily tell they share the same IP class, as the first decimal number is identical.

In a Class B address, the first two octets are the network portion and the remaining two are for the hosts.

In a Class C address, the first three decimal numbers are for the network, and the last octet shows the hosts.

As you can imagine, the smaller the hosts part, the fewer the potential hosts (i.e., devices on the network) can be. That's why Class A networks are by far the largest.

Now let’s find out:

What Is DHCP?

As we’ve seen, no two computers can have the same IP.

This means if network administrators were to assign IP addresses manually, they would have to do a lot of cross-checking to avoid duplication.

This is where a DHCP server proves handy.

It automatically issues unique IP addresses and configures other network information.

DHCP stands for Dynamic Host Configuration Protocol, and it runs at the application layer of TCP/IP.

In large networks, a single Linux or Windows network server could perform the role of a DHCP server.

In most homes and small offices, the router performs this role.

How Does DHCP Work?

DHCP follows the DORA process to dynamically assign IP addresses.

D stands for discovery, O for offer, R for request, and A for acknowledge.

The process goes something like this:

Stage 1 – Discovery

When your computer connects to a network, it issues a broadcast message:

“Howdy, DHCP server! Can you give me an IP address?"

Stage 2 – Offer

Upon receiving the request, the router or DHCP server gets to work.

It unknots the bag containing unused addresses, picks one, and replies:

“Hi there, this one — 192.110.1.3 — can be yours for the next three hours if you want it.”

So in the second stage, the DHCP offers an IP and says for how long it is going to be available.

Step 3 – Request

Your computer takes the IP.  Next, it responds with a message to accept the offer.

Its response might be something like this:

“Oh, thanks, man! So I’ll use 192.110.1.3 from now on.”

Step 4 – Acknowledge

The DHCP server now updates the network server with the IP address and other networking information related to your computer.

It then sends an acknowledgment message:

“You’re welcome. Come back in 3 hours and I’ll issue you another one. Till then, so long!”

Finally, your computer accepts the IP address and plays with it until the time is up.

If you want, you can force the DHCP server to give you a new IP address.

Want to find out how?

Well, that’s up next.

Renew IP - How to Renew IP Addresses on Mac, Windows, and Linux

Sometimes you might have to manually renew your IP address, like when you change your router’s IP address.

Renewing IP address is a two-step process.

First, you force the DHCP server to release your current IP address.

Second, you request the DHCP server to issue you a new IP.

How to Renew IP address on Win 10

Here are the steps to follow:

1) Press the Windows key and X key simultaneously

2) Now, click at Command Prompt

3) In the command prompt window, type ipconfig /release and press Enter. This will release your current IP configuration.

4) Next, type ipconfig /renew and then press the Enter key. The DHCP server will hand over a new IP address to you.

How to Renew IP address on Mac OS

Here are the steps to follow:

1) Click the APPLE button and then click System Preferences.

2) Next, click on Network.

3) If you use Wi-Fi, choose the Wi-Fi option in the left pane; otherwise, select Ethernet. Next, click the Advanced button in the right panel.

4) Click the TCP/IP tab, and then click the Renew DHCP Lease button.

How to Renew IP Address on Linux

Here are the steps to follow:

1. Run the following command to force the release of your IP address: $ sudo dhclient -r
2. Now run this command to request a new IP address: $ sudo dhclient

Wrapping Up

So what have we learned today, folks?

We discovered the answer to the “what is IP” question.

That every computer on a network or a website on the internet (the largest of all networks) has a unique address — called IP address or simply IP.

We also found out what powers the internet: the TCP/IP stack.

It is a combination of two protocols — TCP and IP — that work in tandem to ensure smooth transmission of data over the internet or a network.

Finally, we learned there are two variants of IP addresses (IPv4 and IPv6), as well as how to renew your IP address.

And with that, we’ve come to the end of our exploration of what is IP.

See you next time.