Cisco Certified Network Associate certification resources
In computer networking, every device—a laptop, server, or router—must decide how to forward data packets to their destinations. While routers specialize in forwarding traffic across networks, hosts (end devices like PCs) also make critical forwarding decisions using subnetting, routing tables, and protocols like ARP or IPv6 NDP. This article demystifies how hosts and routers make forwarding decisions, with […]
As we discussed earlier, IPv6 is the improved version of the internet protocol. The IPv6 header is one of the significant improvements over the IPv4 header. The header format has been dramatically simplified. Some header fields have been removed, and others have moved to the optional IPv6 Extension Header. The IPv6 header is only twice […]
The IETF developed IPv6 addresses to overcome the limitations of IPv4, meeting current and future network demands. In 2025, its 128-bit address space addresses the global IP shortage. It is an excellent development with features that better suit current and future network demands. In 2025, IPv6 adoption has accelerated due to the global surge in […]
When the IPv4 address was invented, it was not expected that the Internet would become so popular that millions of devices would use these IP addresses. The IETF defined IPv4 addresses in RFC 791, published in 1981. The first design of IPv4 did not anticipate the Internet’s growth, which created many issues that proved that […]
In 2025, the IPv4 packet header remains widely used despite IPv6 adoption, supporting legacy systems and critical applications like industrial IoT, where its compact structure is advantageous in constrained environments. The network layer converts transport layer segments into packets, with the IPv4 packet encapsulating the data unit and adding header information. In 2025, this process […]
Connectionless No connection is established with the destination before sending data packets, defining a communication model where packets are sent without ensuring the recipient’s availability. This mirrors sending a letter without prior notice. In 2025, this efficiency supports real-time data in IoT, though retransmissions may increase with network congestion. Connectionless data communications work on the […]
The primary function of the network layer is to deliver packets from source to destination across multiple networks. It also specifies the packet structure and processing used to carry the data from one host to another. The layer routes the packet through different channels to the other end and acts as a network controller. Analogy […]
Auto-MDIX (Automatic Medium-Dependent Interface Crossover) is a feature supported on Cisco switches and routers that automatically detects and configures the required cable type (straight-through or crossover) for Ethernet connections. This eliminates the need for network administrators to select or use specific cables when connecting devices manually. Historical Context In the past, connecting two network devices […]
Duplex and Speed settings are the most basic settings for each switch port. By default, Cisco switches will auto-negotiate the speed and duplex settings. However, the switch port and connected devices, such as a computer or another switch, can mismatch the duplex and speed settings. Two types of duplex settings are used for communications on an […]
Ethernet switches employ memory buffering to manage data traffic efficiently, ensuring frames (data units) are temporarily stored when destination ports face congestion. Effective buffering is crucial to prevent frame loss, which can degrade network performance, increase latency, and trigger retransmissions, ultimately impacting user experience and reliability. This article explores buffering methods, their evolution, and their […]