OSI Model

Layer 7 (Application)

Closest to the user or application that is creating the data to be transported across the network, examples are, Microsoft Edge, Outlook, Firefox or even Word and Excel saving a file to a shared drive of OneDrive.

Layer 6 (Presentation)

This is the layer that takes the data from the Application layer and transforms it to the correct format ready for sending

Layer 5 – Session

When two devices, computers or servers need to “send data” to one another, a session needs to be established, and this is accomplished by the Session Layer. Functions at this layer involve setup, coordination and termination between the applications at each end of the session.

Layer 4 – Transport

The Transport Layer deals with the coordination of the data transfer between end systems and hosts. How much data to send, at what rate, where it goes, etc. The best known example of the Transport Layer is the Transmission Control Protocol (TCP), which is built on top of the Internet Protocol (IP), commonly known as TCP/IP. TCP and UDP port numbers work at Layer 4, while IP addresses work at Layer 3, the Network Layer.

Layer 3 – Network

Here at the Network Layer is where you’ll find most of the router functionality that most networking professionals care about and love. In its most basic sense, this layer is responsible for packet forwarding, including routing through different routers. You might know that your Boston computer wants to connect to a server in California, but there are millions of different paths to take. Routers at this layer help do this efficiently.

Layer 2 – Data Link

The Data Link Layer provides node-to-node data transfer (between two directly connected nodes), and also handles error correction from the physical layer. Two sublayers exist here as well – the Media Access Control (MAC) layer and the Logical Link Control (LLC) layer. In the networking world, most switches operate at Layer 2.

Layer 1 – Physical

At the bottom of our OSI model we have the Physical Layer, which represents the electrical and physical (hardware) representation of the system. This can include everything from the cable type, radio frequency link (as in an 802.11 wireless systems), as well as the layout of pins, voltages and other physical requirements. When a networking problem occurs, many networking pros go right to the physical layer to check that all of the cables are properly connected and that the power plug hasn’t been pulled from the router, switch or computer, for example.



To use SSL or to Not, on your WordPress site is a very real question.

Do you allow

  • login to your site
  • have a membership list
  • allow filling in of forms with clients personal information
  • Accept orders on your site

If you answered yes to any of the above questions you will need to use SSL to encrypt the data between your server (the source/Host), the client and their Browser (Chrome, Safari,  Firefox or Edge). Google has embarked on a campaign to discourage browsers from accessing sites that do not have SSL enabled. This has always been associated with cost and the type of security and protection you need is directly related to the cost of the certificate required. Hosting companies supply a service and sell certificates  on behalf of the major companies. Most small and new websites that are created on a host cannot justify the cost of a digital certificate for their new venture.

Help is on its way!

Let’s Encrypt is a free, automated, and open Trusted third party certificate authority (CA), run for the public’s benefit. It is a service provided by the Internet Security Research Group (ISRG). This service relies on donations from its members to be able to continue to provide the free certificates.

  • Free: Anyone who owns a domain name can use Let’s Encrypt to obtain a trusted certificate at zero cost.
  • Automatic: Software running on a web server can interact with Let’s Encrypt to painlessly obtain a certificate, securely configure it for use, and automatically take care of renewal.
  • Secure: Let’s Encrypt will serve as a platform for advancing TLS security best practices, both on the CA side and by helping site operators properly secure their servers.
  • Transparent: All certificates issued or revoked will be publicly recorded and available for anyone to inspect.
  • Open: The automatic issuance and renewal protocol will be published as an open standard that others can adopt.
  • Cooperative: Much like the underlying Internet protocols themselves, Let’s Encrypt is a joint effort to benefit the community, beyond the control of any one organization.

This service has been incorporated by a few of the Hosting companies and allows you to automatically select the free service and have the certificate installed in your domain. Before you register or start a new domain verify that your hosting company allows the use of “Let’s Encrypt” certificates or like me you will have to decide to either pay a fee for one or move your hosting to a company that does offer the free service.