In this blog I usually share practical configuration examples and how-to guides about Cisco networking devices and technologies (routers, switches, ASA firewalls etc). However, there are a lot of people out there interested in more generic and fundamental networking topics because they either just starting out in this field or are learning the basic concepts […]
10 Best Network Troubleshooting Software Tools (Free&Paid)
As a network engineer, you will be spending almost half of your time in troubleshooting issues arising in the network or solving problems related to IT and network conditions. Although there are several Windows or Linux commands that you can use on host computers to check for various connectivity issues, a professional should have a […]
DNS Port Number – What is Domain Name System – How DNS Works
DNS (Domain Name System) is the system that translates an Internet or Host name (that is easier for people to remember) to an IP address. In this article we’ll describe how DNS works, what port numbers are used for DNS protocol etc so keep reading for all info below.
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What is DNS A Domain […]
How to Configure Static Routing on Cisco IOS Routers (Examples)
Cisco IOS Routers support both static and dynamic routes. In small networks (2 to 5 routers) I would suggest to configure only static routes, especially if the network is not going to change much over time. Of course dynamic routing (using dynamic routing protocols such as RIP, OSPF, EIGRP) is much more flexible and scalable […]
What is a Subnet Mask Used For (on Routers and Hosts)
This is a post for people new to networking that have just started learning IP addressing and the basis of routing and subnetting. Every host or device on a TCP/IP network MUST have an IP address assigned in order to communicate with other devices. An IP address consists of a network part and a host […]
10 Best Computer Networking Books for Beginners & Experts
I have read tens of books (both in ebook format and also hard copy textbooks) in my networking professional career over the last 18 years. In fact, all of my preparation for my Cisco and other IT certifications was based on book studying (in addition to hands-on practice of course). Personally, I believe that having […]
Intelligent DDoS Mitigation System – IDMS Compared to Firewall & IPS
As e-commerce continues to proliferate and deliver profitable results, more business is being done online. The growing adoption of online retailing, Internet banking, cloud-based data storage and other commercial services represents a natural evolution of Internet use. For online businesses, however, any downtime can dramatically impact the bottom line. As a result, the growing scale […]
Difference Between Routers and Switches in TCP/IP Networks
The key difference between routers and switches in TCP/IP networks is that Switches primarily function to provide Layer 2 connectivity and Routers provide Layer 3 connectivity (as described in the OSI layer model). What exactly does this mean? From a high level view it means that switches allow hosts to communicate as long as they […]
How to Ping a Network Port (TCP) Number to Verify if its Open
In this article I’ll describe a few ways to verify over the network if a remote TCP port on a host is open or not. This is a popular troubleshooting method to identify if a specific service or application is running on a remote server or computer. As you might know already, when an application […]
Ubiquiti Unifi Security Gateway (USG) Vs Edgerouter 4/Lite
Ubiquiti manufactures networking products (routers, switches, wireless etc) that can serve in a broad range of implementation cases, from Home networks up to large Enterprise environments. The USG (UniFi Security Gateway) and EdgeRouter devices are two product lines that target a similar market – I would say the SOHO and SMB enterprise market (although there […]
Differences Between TCP and UDP in IP Communication Networks
TCP (Transmission Control Protocol) and UDP (User Datagram Protocol) are both Layer 4 transmission protocols in the OSI model. However, these two protocols are quite different. From a high level view you could say that TCP is reliable and UDP is unreliable. Why then would we use UDP?
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UDP Characteristics Due to UDP being […]
Best Ethernet Switches of 2020 – Gigabit-Managed-Unmanaged
Ethernet Switches are the backbone of any network, no matter if it’s a home, office or enterprise network. Even though most of our communication nowadays is carried out wirelessly (WiFi, Mobile 3G-4G-5G etc), there ARE a lot of cases whereby network connectivity has to be implemented the “old-school” wired way. And that’s where Ethernet Switches […]
Classless InterDomain Routing (CIDR) Cheat Sheet – Guide & PDF Download
CIDR was invented to facilitate better and more efficient allocation of IP addressing and especially IPv4 addresses which started running out pretty fast when the whole Internet accelerated its pace during the last 2-3 decades. What is Classless Inter-Domain Routing (CIDR) As you know, an IPv4 address consists of 32 bits and is represented as […]