EZELINK reliable and high-quality Guest wifi solutions equipment with extensive research & development in wireless technologies delivering successful projects in every industry irrespective of their size and complexity. Our specialists have the appropriate education, knowledge and experience, so you can rely on us.

We are beginning to make requirements for the devices, Wifi6 wireless solutions be it a laptop, tablet computer or any other specialized equipment. That is why more and more often there is a need for modernization or implementation of wireless networks, which can exist in parallel or completely replace the wired network.

Wireless Technologies

Current stage of development of wireless technologies allows using Outdoor wifi solutions and Wi-Fi networks to solve almost any problem of building an access network, be it an office, hotel, shopping center or cottage village. When considering the implementation of an external (street) Wi-Fi network project, it is worth paying attention to the fact that in the absence of a large demand for Wi-Fi at the moment, it is enough to introduce one or more access points instead of covering the entire facility with wireless coverage. And then, as requests come in, gradually expand your business. This method of developing a wireless network will reduce the likelihood of costs and the size of the initial investment.

Wi-Fi Solutions for Small Businesses

Small business solutions are simple, cost effective and fast to install. Wireless access in such solutions is provided for access to the internal network and the Internet. Support for voice and video communications, as well as streaming data, is significantly limited. Typically, the number of access points in these solutions does not exceed 4-5, with about 6-8 clients connected to each. Such configurations do not require the use of hardware controllers; all access points are configured separately. To manage the network, it is necessary to carry out identical manipulations with each point separately, which requires higher qualifications of IT personnel and reduces the functionality of the system as a whole.

Corporate WiFi Solutions

In installations of this level, hardware controllers of wireless Wi-Fi networks are always used. Solutions of this class assume the use of up to 3000 access points, and support the simultaneous operation of up to 30,000 client devices. When using specialized radio sensors and access points with the function of monitoring the radio broadcast, a system for determining the location of subscribers, sources of interference and intruders posing a threat to the security of the network can be implemented. At the same time, the system has the ability to self-repair: in the event of interference, a dynamic selection of the channel least affected by the interference occurs. Fail-over mechanisms are implemented. If an access point fails, its clients are intercepted by neighboring access points without losing the connection.

Hotels, Restaurants and Cafes WiFi

The specificity of Hotel wifi solution for hotels, restaurants involves the use of a wireless network for Internet access, e-mail, VoIP telephony and video communication. Such schemes do not require the implementation of client roaming functions without breaking the connection, since the main traffic flow comes from fixed points. A software controller can be used to configure and monitor access points. To ensure the security of guests’ data and to facilitate the configuration of client devices, WPA2 password-based encryption is used, since this excludes the possibility of eavesdropping on the air and intercepting confidential information. For the convenience of administration and sale of Internet access services via Wi-Fi, you can provide a Personal Account for each mobile subscriber.

Education WiFi

In addition to commercial use, the trend of deploying Wi-Fi networks in educational institutions is gaining momentum. In schools and universities, wireless access from tablet PCs completely translates the entire educational process into an interactive environment, which significantly improves the quality and level of education. To attend lectures, it is not necessary to be physically in the classroom; the issue of access to information carriers is being resolved: paper manuals, libraries, timetables. Interaction between teacher and student becomes available anywhere in the world.

Healthcare WiFi

Using Cloud managed wifi solutions in medicine means instant access to the most up-to-date information from the Internet, any reference manuals, the ability to write prescriptions with one touch of the screen, storage and backup of all patient records on servers, etc.

Wireless Solutions For Telecom Operators

The main problem when deploying a cellular network is the limited bandwidth of each cell. All the speed available to the base station is divided between the subscribers. To increase the speed, operators are trying to reduce the number of subscribers, reducing the coverage area of ​​each cell. This entails unreasonably high costs for increasing the number of expensive base stations to cover the same area. In this case, Wi-Fi is used. Cheap Wi-Fi hotspots provide Internet access exactly where you need it most. Subscribers’ voice calls are made through the existing GSM and 3G networks. There is no need to deploy additional 3G base stations. In another scenario, Wi-Fi is deployed in conjunction with short-range cells (pico and femto cells) in places with the highest subscriber density, to reduce the load on cellular base stations.

In addition, the vast majority of mobile devices are equipped with Wi-Fi, even entry-level tablets and e-readers that do not have any other wireless communications. All these devices can be connected via Wi-Fi to the operator’s networks, expanding the subscriber base and increasing the economic feasibility of deploying such networks. The same situation is observed in 4G networks (WiMAX / LTE). These technologies are often used as a backbone to deliver traffic to specific points. This traffic is then distributed locally over the Wi-Fi network. This process is called offload. At the same time, the subscriber of the cellular network continues to receive voice calls and SMS through the cellular network, and all Internet traffic goes through Wi-Fi. At the same time, Internet telephony and video conferencing services such as Skype and Lync remain available. Billing for Wi-Fi at local points can be organized in any available way: through payment terminals, paid SMS with temporary passwords, etc.

BYOD (Bring Your Own Device)

The BYOD concept is a security policy under which company employees are allowed to bring their own portable devices (laptops, tablets, communicators) to the workplace and use these devices to access the company’s privileged data and services. The term is also used to describe the same practice in educational institutions where students use personal devices for educational purposes. With this approach, all corporate security policies are implemented, the local network remains protected from possible threats. It is more convenient for staff and students to work from their personal devices, and this practice has become a general trend. Our task is to design and configure a Wi-Fi network in accordance with the modern needs of the Customer.

High Level of Security

Wi-Fi uses sophisticated encryption methods that cannot be bypassed or “broken” with modern computing power. Access is provided both by password and by a security certificate. Logging into a wireless Wi-Fi network is as secure as connecting to a corporate switch port.

WiFi Scalability

Not every implementation requires further scalability (e.g. hotels, restaurants, cafes). But if you are faced with the task of building a scalable wireless network, then the main point is the choice of the manufacturer and the line of access points. Not all access points scale from a standalone access point to a cloud of lightweight access points managed by a Wi-Fi controller. In scalable wireless networks, the first step is to install and configure multiple access points. The development of the company and the increase in needs will not entail a complete replacement of equipment. It will only be necessary to update the software (firmware) on the existing access points and add wireless components.

WiFi Seamless Roaming

To implement voice (VoIP) or video communication, the corporate infrastructure uses fast roaming mechanisms (analogous to handover in cellular networks). The Wi-Fi wireless network controller transfers service to mobile subscribers as they move from one access point to another without delays or packet loss.

Automatic control and management of radio resources of the system. The WLAN controller performs dynamic redistribution of frequency channels and transmitter powers of access points according to specified algorithms. This reduces the level of interference created by neighboring points. Mechanisms of redundancy of access points are implemented – if one of the devices fails, the neighboring points increase the power and “intercept” clients, the service does not suffer.

Protection of radio air from interference and malicious clients. Standard Wi-Fi wireless LAN equipment is not capable of detecting interference from non-IEEE 802.11 devices. The task of monitoring the radio broadcast falls on access points with an additional spectrum analysis function, or specialized radio sensors that complement the infrastructure of a wireless Wi-Fi network. In some cases, this role is assumed by access points that are switched to analysis mode and do not serve clients. After detecting interference, the system rebuilds the channel plan of the access points. Moreover, so that channels adjacent to interference are assigned to access points that are as distant as possible from their sources. In addition, the system allows you to record attempts to “jam” the network and block malicious attempts to guess the access password.

Determining the location of devices. Dedicated services running on the Wi-Fi controller allow you to determine the location of emitters based on the signal strength received by multiple access points. These include both client gadgets and computers, and sources of interference (microwave ovens, cameras), malicious devices (“jammers”, access points – twins). The system determines their location and displays them on the floor plan. There are several options for the implementation of such systems, their accuracy is about 3-5 meters. Location data can be used to collect statistics, as well as to prohibit the use of mobile devices in certain areas on the building map, for example, meeting rooms or bathrooms.

Consistently high access speed. To ensure high speeds of access to the network, it is necessary to fulfill a number of factors, the main of which remains the competent design of the WLAN. The job of the surveyor or point placement engineer is to provide continuous coverage throughout the building. In this case, the system must be configured in such a way as not to accept connections from clients outside of a stable connection. In this case, the network will not be overloaded with re-sending packets, and all clients will be provided with a guaranteed connection speed, regardless of the load of each.

Increased user loyalty. In the service sector (hotels, hotels, hostels, restaurants, cafes, bars, business centers, shopping centers and malls, etc.), the provision of free Wi-Fi Internet access services significantly affects the client’s attitude to the service provider and increases “stardom”. For some potential customers, being able to access the internet is critical. In large malls, shoppers receive additional information and product reviews online and are more likely to shop. In addition, on the basis of free access to a wireless Wi-Fi network, an interactive product catalog can be implemented on the web portal platform, as well as a shopping cart, contextual advertising, an interactive shopping center scheme, and other services.

WiFi Web Authentication

Popular solution for hotels, airport terminals, shopping centers. Its essence is that a mobile subscriber connects to a Wi-Fi network without a password, opens an Internet browser and enters an arbitrary URL. The authorization system automatically redirects him to the authentication page, where he can enter a username and password. After successful input, the user gains access to the Internet. Web authentication systems are also popular in corporate wireless Wi-Fi networks, where data from Active Directory are used as login and password.

Guest portal for hot spots. Often in places with open access, before getting on the Internet, users go to the service provider’s page (restaurant, store, mobile operator, etc.). From where, after viewing the mandatory advertisements, the client is redirected to the Internet. This approach is similar to web authentication, but does not require a username / password pair. The portal is a web page on the basis of which any web services, statistics collection services, connection duration, etc. can be implemented. It should be noted that advertising covers the costs of clients’ Internet access, which, among other things, may be limited in speed / time / volume, etc.

WiFi Quality of Service (QoS)

The Quality of Service (QoS) mechanism classifies traffic by type and importance, sending high priority data packets first. Without this mechanism, it is impossible to simultaneously pass large amounts of simple data and voice communication (VoIP – Voiceover Internet Protocol) or video conferencing over the network. In the absence of this technology, the connection “croaks”, is interrupted, the image of the interlocutor is fragmented and covered with “squares”.

Designing and installing Wi-Fi wireless networks is a complex engineering task, in the solution of which specialists from several directions take part. In order for the network to meet all customer requirements and provide a reliable service, at all stages of implementation, the requirements for the placement of access points, antenna orientation, installation of SCS for powering access points via PoE and connections with switches are strictly met. Equipment tuning done by engineers who have knowledge of the technique and physics of radio wave propagation, as well as have experience with the equipment installation. Otherwise, you may be sold a large amount of equipment that individually meets all the requirements, but installed in such a way that it is a “pile” of expensive non-functioning “hardware”. Our specialists have the appropriate education, knowledge and experience, and are also certified for industry leading standards, so you can rely on us. This is evidenced by EZELINK, successful projects and the confirmed qualifications of our engineers.

Dynamic Host Configuration Protocol (DHCP) assigns IP addresses to devices on a network. It centralizes address ownership so that no single device on the network has a permanent address. DHCP is part of the TCP / IP suite of protocols and is considered an application layer protocol in the TCP / IP stack.

The protocol allows network Guest wifi solutions administrators to assign addresses to devices connected to the network. The address format that the system uses is an IP address, which is defined in the Internet Protocol – another part of the TCP / IP protocol suite.

DHCP is commonly used by ISPs to assign IP addresses to clients. This system allows ISPs to use the address pool more efficiently. Not all ISP clients are connected to the Internet at the same time, so home users are no longer assigned permanent addresses . Wifi6 wireless solutions Instead, each is assigned an address for the duration of the connection. Private Wi-Fi routers implement the same method for the networks in which they operate.

IP addresses must be unique within the network they access. Thus, on a private network, IP addresses do not have to be unique globally, only on that network. Outdoor wifi solutions IP addresses connected to the Internet cannot be duplicated anywhere on the Internet. DHCP deals with the allocation of IP addresses from a reserved pool. 

What is DHCP?

The protocol establishes procedures for requesting and allocating IP addresses on a network. These definitions include a series of message types that the distribution process must include.

Like all other protocols supported by the IETF, DHCP is not a program. It is simply a set of standards that anyone who wants to create software for the DHCP address allocation function must follow. The importance of publicly available networking standards is that they Guest wifi solutions ensure the compatibility of networked programs no matter where in the world they were written.

A key element of the DHCP method is the procedure that the client initially uses to communicate with other devices on the network. As all computers on a network need a unique address to communicate , the question of how any computer can communicate to obtain an address is a mystery that DHCP solves.

The DHCP methodology is defined in a document that is publicly available and maintained by the Internet Engineering Group. The IETF presents the current protocol status on its website as RFC 3942. This document defines DHCP version 4. The original system definition is Wifi6 wireless solutions contained in two documents: RFC 2131 and RFC 2132 .. There is a collection of additional protocol definitions that complement the standard published in RFC 3942 . . For example, RFC 4242 explains how to adapt the protocol to use IPv6 addresses.

How DHCP works

There are two main elements of a DHCP system. They are DHCP server and DHCP client. A DHCP client is found on each of the devices you have connected to your network. Outdoor wifi solutions When this device is turned on, the DHCP client starts up as part of the operating system startup procedures.

The device does not have an IP address and therefore cannot send messages with a return address. Instead, the client includes its MAC address in the message. Wifi solution The MAC address is actually the identifier for this device’s network card. The MAC address of every network card in the world is unique.

The DHCP initialization process includes four types of messages:

• opening
• Offers
• Inquiry
• the confirmation

This is how these four messages, collectively abbreviated as DORA , implement the DHCP process.

DHCP Discovery

DHCP uses connectionless user data protocol for transmission. The request that the client sends is called the discovery message. The protocol calls this message type Hotel wifi solution DHCPDISCOVER. UDP is a connectionless system, so there is no initial session establishment phase.

This is the first Discovery message sent over the network by the client. This means that it has not been sent to a specific address. This is because the DHCP client does not know the DHCP server address at this point.

Although it should be possible for each client to configure the network DHCP server address recorded in the configuration, the assumption of not knowing the address makes it easier to configure and manage DHCP. If you do not need to manually specify the DHCP server address to the client when adding a device to the network, the discovery operation becomes a universal procedure. … Any device can have a DHCP client loaded onto it as part of its firmware, and it is automatically placed on Guest-wifi solutions whatever network it is added to.

The lack of a fixed destination address also means that you can move a DHCP server from one computer on the network to another without having to go to every device on the network and without resetting that server’s address.

There is one fixed parameter for communication between clients and DHCP servers: the port number. UDP port # 67 is reserved for DHCP servers and UDP port 68 is reserved for DHCP clients. Thus, the transmission of the Discovery message does not bind the processors of other devices on the network. This is because only the DHCP server procedures will listen on the network for messages addressed to port 67. All other devices on the network simply ignore the message, since it is not sent to port 68 ..

DHCP offer

The response returned by the DHCP server is structured as Cloud managed wifi solutions DHCPOFFER. This message is sent over the network, so every computer on the system will receive it. This is UDP port 68, so the DHCP client on every network device will pick it up .

The intended recipient’s MAC address is contained in the message, so all other devices on the network will simply discard the message as soon as they see that it’s not for them.

The message contains the suggested IP address for the client. It also includes the duration, in seconds, that the device can use this address for. The allocation of IP addresses in DHCP is temporary and is called a “lease”. Duration is the lease time, or how long the client will keep this IP address.

Other information in the Offer message includes the subnet mask to be used for the network, DHCP server address, router address, and DNS server addresses on the network. With these addresses, the DHCP client can configure the network software on the device and fully integrate the hardware into the network.

DHCP request

You might think that allocating an address from a DHCP client by a DHCP server would be the end of the process. However, the situation is a little more complicated because the Protocol takes into account the possibility that multiple DHCP servers may be running on the same network. …

If there is more than one DHCP server on the network, the Discovery message that is sent to all devices on the network will be accepted by all DHCP servers. Each of them will send back an offer, so the client will receive multiple addresses. The client chooses one of these addresses, which is usually the first one it receives, and then sends back a request message confirming the use of that address.

At this point, the client has the IP address of the server that sent the selected offer message. However, the Request message is not addressed directly to this server. This is because all servers that send “Offer” messages need to receive a “Request” message containing the selected IP address.

The server that allocated the selected IP address receives a request message and records that the proposed address is currently in use. Other servers that submitted suggestions also receive this request message , find out that their addresses were not selected and leave those addresses available for the next Discovery message to be broadcast on the network. The protocol refers to the structure of the request message as DHCPREQUEST.

DHCP confirmation

The final step in the DHCP initialization process is a DHCP acknowledgment message sent by the server that provided the selected IP address. This message is defined in the protocol as DHCPACK. None of the other DHCP servers on the network send this message back.

Curiously, even if the client claims to be using the offered IP address, the DHCPACK is not sent directly to that address, but is sent again to all devices on the network.

DHCP client functions

The DHCP client does not get an IP address all the time. The lease time of the allocation depends on the network policy, and different lease terms may be set for different types of equipment. If the lease expires, the DHCP client must apply to renew it.

The update process is exactly the same as the initial discovery process, except this time the client has an address where it can contact the server that allocated that address. So, instead of sending a Discover message, the client can contact the DHCP server directly . The client can request the same IP address, or the network policy can dictate that each update should be performed with a replacement IP address.

Two additional message types in the DHCP definition are intended for use by the client: the DHCPINFORM message and the DHCPRELEASE option.

DHCP Inform

The DHCPOFFER message consists of several option fields in the packet structure. However, the server rarely uses all of this and does not matter to any. A specific client program may need specific information to properly configure its device on the network. If this important information is missing from the DHCP offer message, it may send a Report message asking for details. If this information is available, it will be sent by the server in the form of another offer message with mandatory filling of the parameter fields. … An example of the use of DHCP Inform is that the browser often uses this message as a way to obtain Web proxy settings through automatic Web proxy detection routines.

On Windows Server 2003, DHCP servers use the Inform message type to detect rogue DHCP servers.

DHCP release

The release message is sent by the client to end the lease on the IP address before the specified period expires. This type of message is not essential in protocol operations because regular lease termination ahead of schedule usually occurs when the user turns off the device. There are no procedures to delay the shutdown process to allow the DHCP client to send a release message. In this case, the IP address remains allocated to this client until its lease expires, even if the device is not active during this period.

DHCP is only concerned with the allocation of available IP addresses. It does not support communication with network nodes. The IP address is assumed to be in use for the duration of its lease, and therefore it does not verify that the device to which the IP address is allocated is still active on the network . If the network configuration is changed, the DHCP manager does not make any efforts to redistribute addresses. These restrictions explain why DHCP is typically implemented as part of a suite of network addressing protocols called DDI, which is explained below ..

DHCP server functions

Dynamic Host Configuration Protocol includes three methods for allocating addresses to a server. These:

• Dynamic allocation
• Automatic distribution
• Manual distribution

Here is more detailed information on each of these modes of operation.

Dynamic allocation

This is the standard distribution method used by DHCP and follows the procedures outlined above. The server is configured with a range of IP addresses known as scope in DHCP terminology. This range may not be contiguous, so it is possible to declare exceptions within an address scope. Exceptions can also be defined as a range.

Automatic distribution

In this case, the server maintains a list of previous IP address assignments for the MAC addresses of devices on the network. When a new request comes from one of these addresses, the server will allocate the same address again. With automatic allocation, the address is assigned not only to the device, and therefore there may be cases when the previously used address has already been allocated elsewhere, and the server will send a different address to this device.

Manual distribution

In this option, the DHCP server reserves an IP address so that it can only be assigned to a specific MAC address. This means that each device receives the same address every time it connects to the network. You can mix manual allocation with dynamic or automatic allocation. If the device’s MAC address is not on the reservation list, you must use one of two other methodologies to allocate the address. This system is also known as static allocation, static DHCP, fixed address allocation, address reservation, DHCP reservation, IP address reservation, and MAC / IP address binding.

Other DHCP Hosts

Large networks are often subnetted to prevent delays caused by too many devices trying to access the transmission medium. In these cases, the network can still only work with one DHCP server, but it requires a relay device on each subnet.

The packet structure of all types of DHCP messages includes a field called GIADDR that is populated by the relay. This is the relay’s own address, so when a message received by the relay from the client is forwarded to the DHCP server, the server knows where to send the response and what address range to use to allocate the address on that relay. subnet.

When the relay agent communicates with the DHCP server, both devices use UDP port 67.

DHCP security weaknesses

DHCP uses the User Datagram Protocol. It is a connectionless communication system, so it does not include encryption. Since almost all types of messages in the protocol are designed to be broadcast in every network mode, snoopers can gain a lot of control over network operations and create a devastating violation by simply gaining access to the network and listening to DHCP broadcasts.

This is why DHCP is rarely used in isolation. There are a number of coordination issues to consider when allocating IP addresses. … These addresses must also be referenced by the DNS server. There is a possibility that an attacker could inject a virtual spoofed DNS or DHCP server into the network. Network security and address validity are ensured by the IP address manager. It is a key element in the DDI suite of solutions.

DNS, DHCP, IPAM – together they form what we often call DDI. They all work together to manage, assign and resolve IP addresses and form an important part of any network.Read on as we explain what each of these components are, what they are used for, and why you need them.

Today we’ll start our journey by discussing IP addresses, what they are and why we use them Guest wifi solutions . Then we will introduce the DHCP system, how it works and what are its various components. After that, we will discuss the interaction between DNS and DHCP and why it is so important. And we’ll end this crash course by explaining what DDI is and why it’s so important Wifi6 wireless solutions. 

IP addresses are at the very center of the Internet. They uniquely identify each device connected to the network. An important distinction needs to be made between public IP addresses and private IP addresses. The first are those used on devices connected to the public Internet. For example, a web server often has a public IP address. Outdoor wifi solutions The Internet router installed by your ISP in your home also has a public IP address. On the other hand, private IP addresses are the ones we use on home and corporate networks. They must also be unique, but only within a specific network.

IP Address

Back in the history of the Internet, when the IP protocol was defined, each connected device was manually configured with a separate IP address. We called it static or fixed IP addressing. This was cumbersome but ok as the number of connected hosts was low. As networks (both public and private) grew, it became more difficult to manually configure IP addresses as the process was error prone and often resulted in duplicate IP addresses on the network. It took until the early 1990s before a durable solution was introduced in the form of DHCP. Wifi solution

DHCP System

The Dynamic Host Configuration Protocol – or DHCP as we commonly call it – was invented to dynamically assign IP addresses and provide connectivity to connected hosts.DHCP eliminates the need to manually configure IP addresses. Hotel wifi solution DHCP not only configures IP addresses, it can configure most of the network parameters of the connected host, such as IP address, subnet mask, name servers, WIND server (s) in Windows environment, and a few other parameters. All parameters are dynamically configured every time the host is started on the network. 
How it works

No matter what the exact parameters are configured by DHCP, the process for configuring a host is always the same. This is a four-step process called DORA, which stands for Discovery, Request, Offer, and Acknowledgment. Guest-wifi solutions This is what happens when the host starts. 

During the discovery phase, the host sends out a broadcast message – this is a message that will be accepted by any host connected to the network called DHCPDISCOVERY. The message must be forwarded because the host does not know the DHCP server address at this time.

In the second step, the server responds with a DHCP offer. The offer contains all the configuration parameters for the host’s network interface. Now, this is where things get a little tricky. Since there can be multiple DHCP servers on the network, a host can receive multiple offers. When this happens, the host will simply pick one of the suggestions and move on to the next step. Which one should you choose? Usually he chooses the first offer he receives. 

In the next step, the host sends a DHCP request. It includes the offer that he chooses and will instruct the server whose offer he chose to continue, informing other servers that sent offers that they had rejected and that they can release the offered IP addresses Cloud managed wifi solutions .

In the final step, the server sends a DHCP acknowledgment to the host, confirming that it has correctly reserved the proposed IP address for that host.

DHCP client component

DHCP configuration information obtained by the client and used to configure the network interface is not valid forever. In fact, it is leased rather than assigned by a DHCP server. And this lease is about to expire. 

It is one of the most important tasks of the DHCP client to ensure that the interface configuration remains valid. It does this by periodically trying to renew the lease before it expires. The update process uses the same DORA sequence. The only difference is that during the discovery phase, the client requests the same IP address it already has.

Another important function of a DHCP client is the release mechanism. Whenever the client no longer requires its IP address, as it might when it terminates, it will notify the DHCP server to release the IP address so that it can be reused by the server.

DHCP Server Component

As far as a DHCP server is concerned, its main job is to send configuration information to any host that asks for it, and for it to send unique parameters to each individual host. IP addresses can be assigned by a DHCP server in one of three ways: dynamic, automatic, or static. 

Dynamic allocation assigns a new IP address to each IP address. Automatic allocation is similar, except that the server will keep track of which IP address has been assigned to each host and will try to assign the same address to it the next time it connects.

Finally, with manual allocation, the administrator must manually associate a specific host identified by its MAC address with a specific IP address. This is also called DHCP reservation because it reserves a specific address for a specific host.

Interaction between DHCP and DNS

Domain Name Service – or DNS – is used to map host names to IP addresses. On a private network that uses DHCP dynamic allocation, there is often some integration between DNS and DHCP. This way, DNS always knows the current IP address of each host. 

This is why many DHCP servers also include a DNS server. This applies, for example, to the Microsoft DHCP server, which is fully integrated with the DNS server.

The Comes DDI

DDI is an acronym for DHCP, DNS and IPAM, or IP Address Management. We haven’t discussed the latter yet. IPAM refers to any software used to manage IP addresses. Such systems can typically be used to manage both DHCP assigned addresses and statically assigned addresses that are manually configured on hosts. 

With the tight integration that is required between the three, it is quite normal that many vendors have three products built on top of each other, or that they offer all three products separately.