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Category Archives: Networking
Using nslookup to verify DNS registration for domain controllers
The nslookup command is a standard command-line tool provided in most DNS service implementations. It offers the ability to perform query testing of DNS servers and obtain detailed responses as the command output. This information is useful in troubleshooting name … Continue reading
Disable unnecessary network services for security
Whether it is a Windows PC, router, switches, Linux machine or network enable device, it is recommended to stop unnecessary services that are run by default. Every running, but unused, service on your system is an unnecessary security vulnerability. Users … Continue reading
Posted in Networking, Security
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Using POP3 not SMTP to retrieve email
The Post Office Protocol version 3 (POP3) as defined in RFC1939 is an application-layer Internet standard protocol used by local e-mail clients to retrieve e-mail from a remote server over a TCP/IP connection. The protocol defines how the server responds … Continue reading
Trouble shoot domain name issue using nslookup
nslookup is a computer program used in Windows and Unix to query Domain Name System (DNS) servers to find DNS details, including IP addresses of a particular computer, MX records for a domain and the NS servers of a domain. … Continue reading
Study of ARP using Wireshark
Wireshark is a very useful tool for the study of network protocol! In my previous post on ARP, we have learned some basic about the ARP protocol. Let’s look more detail into the ARP request packet in this post. When … Continue reading
ARP resolves MAC address from IP address
A PC in an Ethernet network can communicate with another PC, if only it knows the Ethernet address (MAC address) of that PC. Address Resolution Protocol (ARP) is a network protocol uses to translate a PC’s IP address to physical … Continue reading
Switch as Intelligent Hub
In an Ethernet network, every client, server and network device is wired to a hub or switch. However, what is the different between hub and switch? In a word: intelligence. Answer this in short sentence: Hub versus Switch – Shared … Continue reading
Protocol Data Unit (PDU) – Process of Network Data Encapsulation
Within the layer in the OSI Reference Model, the communication between layers higher than layer one is logical; the only hardware connection is at the physical layer. Communication take the form of some sort of message that is sent between … Continue reading
How to enable CUPS remote administration
CUPS (Common UNIX Printing System) is the standards-based, open source printing system developed by Apple Inc. for Mac OS X and other UNIX-like operating systems. The default installation of CUPS only enable you to manage it from localhost computer. However, … Continue reading
All come back to IP address
We normally use domain name in accessing a homepage like: http://www.yahoo.com However, if your computer is accessing to the Internet directly without using a proxy server, it will need to first resolve this domain name (in this case www.yahoo.com) into … Continue reading