Internet of Things

This protocol was published as RFC 6762, it utilizes IP multicast UDP (User Datagram

Protocol). Apple’s Bonjour and open source Avahi are known for implementing mDNS. The

Android operating system is also known for implementing mDNS. Plus, Microsoft’s latest oper-

ating system, Windows 10 has also implemented mDNS. However, Windows 10 has very lim-

ited use of mDNS for discovering network connected printers.

When an mDNS client requires to solve a hostname, it emits an IP multicast query that

questions the host on having the exact name to identify itself. Then the target machine multi-

casts a note that contains its IP address. All devices existing in that subnet can utilize that data

to update their mDNS caches.

Any host can eectively resign its claim to a domain name by just sending a response

packet consisting of TTL (time to live) equal to zero.

DNS-SD

DNS Service Discovery is a method of utilizing standard DNS servers, programming interfaces

and packet formats to explore the network for services. The DNS-SD library facilitates an easy

and unified programming system for compiling Zeroconf features (hostname resolution and

service discovery) to a C++ application. The DNS-SD library does not focus on its own mDNS

and DNS-SD protocol stacks. Instead, it uses an already existing Zero implementation for this

purpose. You can use Apple’s Bonjour or Avahi as a backend for the DNS-SD library.

The biggest benefit of the library is that it facilitates a unified programming interface. It

becomes completely transparent for the programmer whether he is using Bonjour or Avahi as

a backend.

In simple words, DNS-SD lets you search (and advertise) dierent services on your net-

work. For example printers, chromecasts, and airplay speakers.

Some Notable Features of DNSs-SD:

• It is compliant with standards like RFC 6762 and RFC6763,

• It won’t create interference between existing Bonjour/Avahi installs,

• It can handle hibernate/sleep/wakes without even flooding your network, and

• It is dependency-less.

Data Protocols

MQTT

The acronym ‘MQTT’ is used for “Message Queuing Telemetry Transport”. It works as a light-

weight messaging protocol that facilitates resource-constrained network clients with an easy

way to send telemetry data. Plus, it also uses a publish/subscribe communication pattern. It is

designed to be used with machine-to-machine (M2M) communication. Thus, it plays a crucial

role in the IoT (Internet of things).

MQTT makes it possible for the resource-constrained IoT devices to emit or publish data

about a specific topic to a server that operates as an MQTT message broker. The broker then sends

the data about those clients that had subscribed to the client’s topic earlier. This topic is just like

a hierarchical path. The clients are able to subscribe to a level of a topic’s hierarchy or may utilize

a wild-card charter in the subscription process to subscribe to multiple levels. This protocol is

an ideal choice for wireless networks with dierent levels of latency due to bandwidth limits or

problematic connections. This protocol was designed and developed by Andy Stanford Clark and

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