Category: CCNA

Cisco Certified Network Associate certification resources

CCNA September 21, 2019

Inbound and Outbound ACL Logic

Inbound ACL Logic When a router receives a packet, it starts comparing the information in the packet header with the ACL. If the information in the packet header and an ACL entry match, the rest of the entries in ACLs are skipped, and the packet is permitted or denied as configured by the matching entry....
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Network topology diagram showing routers, switches, PCs, and a server with IP addresses and access-list configurations.
CCNA September 21, 2019

How to Configure Extended ACLs – Exclusive Explanation

The number of extended ACLs starts from 100 to 199 and 2000 to 2699, providing 799 possible extended numbered ACLs. We can also create extended ACLs with the name. Extended ACLs are used more than standard ACLs because of greater control and facilities. Extended ACLs check packet source addresses, destination addresses, protocols, and port numbers....
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CCNA September 11, 2019

How to Configure Standard ACL to Secure a VTY Port

All Cisco routers and switches cannot be accessed remotely via a terminal program like PuTTy and Tera Term by default. There are two methods of remote connectivity, either vty connection or SSH connection. The SSH provides encrypted connectivity, and Cisco recommends it for remote administration. But, if your router’s Cisco IOS does not support SSH,...
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CCNA September 10, 2019

ACL Statistics – Exclusive Explanation

After ACL has configured and applied to an interface and block some traffic then we can check the ACL statistics using the show access-lists command. The command will show ACL statistics for each statement that has been matched. The figure below illustrates some configured ACL statistics. Examine that some match has been found. So when traffic is...
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An illustration of a person working on a laptop with a screen displaying commands for editing standard ACLs, titled "How to Edit Standard ACLs."
CCNA September 10, 2019

How to Edit Standard ACLs

Network administrators sometimes want to edit standard ACLs. As you know, each new entry you add to the Access Control List (ACL) appears at the bottom of the list, and the router assigns a sequence number to that entry automatically. Standard ACL statements are added to running-config files, but there is no built-in way to...
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CCNA September 9, 2019

How to Configure standard ACLs

Standard ACLs permit or deny traffic based on source addresses. They differentiate routes on a network using the IP address. The port and destination of the packet are not evaluated. Standard ACLs only contain a list of addresses or address ranges and a statement as to whether access to or from that address is permitted...
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Diagram of TCP three-way handshake process showing SYN, SYN-ACK, and ACK exchanges between two hosts for connection establishment.
CCNA September 2, 2019

Understanding TCP Three-Way Handshake: A Comprehensive Guide (Updated 2025)

In networking, the TCP three-way handshake (often called a “TCP conversation”) establishes reliable connections, which is crucial for Access Control Lists (ACLs) to filter traffic effectively. ACLs manage inbound and outbound traffic based on IP addresses, ports, and TCP flags. This article explains TCP fundamentals before diving into ACL integration, helping CCNA students grasp transport...
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Diagram and configuration commands for setting up OSPFv3 on a network.
CCNA September 1, 2019

How to Configure OSPFv3: Complete Guide (Updated 2025)

Figure 1 shows the reference topology for configuring OSPFv3. You can also see the commands for configuring OSPFv3 for IPv6 unicast and link-local addresses on the interfaces of Router1. As identified in the referenced topology, assume that Router2, Router3, and Router4 interfaces have already been configured with the global IPv6 and link-local addresses. This topology...
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Illustration of interconnected routers demonstrating link-local IPv6 address concept
CCNA September 1, 2019

What is a Link-Local IPv6 Address – Exclusive Introduction

Routers configured with dynamic routing protocols such as OSPF or EIGRP must send and receive routing protocol messages with their directly connected neighbors. The routers exchange messages between neighbors on the same subnet. These messages are always sent from the router’s source IPv4 address. Link-local IPv6 addresses are perfect for this purpose. The address also...
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nfographic comparing similarities and differences between OSPFv2 and OSPFv3 routing protocols, including link-state features, metrics, areas, packet types, router ID, advertised routes, multicast addresses, authentication, and LSA types.
CCNA September 1, 2019

OSPFv2 vs OSPFv3: Key Differences and Similarities

OSPFv3 is a routing protocol for IPv6, just as OSPFv2 is for IPv4. While both share core principles, there are vital differences in their operation. OSPFv3 serves as the IPv6 equivalent to OSPFv2 for exchanging prefixes, making it essential for modern networks handling dual-stack environments. In IPv6, the network address is referred to as the...
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