slaptijack

You may already know that the IEEE 802.1D specification recommends a maximum network diameter of 7 hops. What you may not know is that the number 7 is derived from a series of calculations based on various timers being tuned to their default values. If you are designing a …

ISC is urging BIND users to upgrade their production DNS servers immediately. ISC recently announced a patch to fix an exploit in BIND. This exploit is in the wild and has been used to crash BIND servers resulting in a denial of service. Using a specially crafted dynamic update packet …

Decision structures (also known as selection structures) are used in programming to take an action based on the result of a question (Farrell, 2008). An if-then-else statement is the most basic kind of decision structure. The question is represented as a Boolean expression that results in a true or false …

Referential integrity and business rules are two subjects that individuals new to database design find confusing. Relational databases use tables to represent things and events. It is often necessary for a table to refer to another table. In this case, the two tables have a relationship. Referential integrity ensures that …

I use VirtualBox to run a Microsoft Windows guest on my iMac. For some reason, VirtualBox did not notify me that version 3.0 had been released. This new version includes symmetric multi-processing (SMP) for guest systems, Direct3D 8 and 9 for Windows guests, and OpenGL support for Windows, Linux …

I saw this error message on a Cisco ASA 5540 today:

%ASA-3-210005: LU allocate connection failed

According to Cisco, this error means the standby unit was not able to create a new connection for stateful failover. The recommendation is to verify that the system has enough RAM.

OK...

# show memory …

For those not acquainted with the vernacular of relational databases, many frequently used terms can be hard to grasp. These terms are often difficult to comprehend, but the concepts they describe can be illustrated in plain English. When a database administrator or developer is working with someone not fluent in …

When planning for a new application, all organizations are faced with deciding whether to develop the application in-house or purchasing an off-the-shelf software package. Developing the application in-house has the benefit of ensuring the application is custom-fit to the organization's needs. Unfortunately, this custom-fit may result in an application that …

Like many other kinds of businesses, a landscaping business needs a billing system. As is often the case, billing systems require an incredible level of customization thanks to the various intricacies of most companies' pricing structures. Designing a billing system to fit the specific needs of an individual organization is …

A database is a collection of files used by an organization in support of its daily operations. The files in a database are commonly called tables because their data is organized into rows and columns. Databases allow for easy storage and retrieval of the data kept within the files that …

The beginning of truly inexpensive data storage began with the introduction of magnetic tape. Unlike previous data storage technologies such as punch cards, magnetic tape has the ability to hold large quantities of data. Additionally, the ability to store data on magnetic data did not inhibit the format of the …

Before a programmer can sit down and create a new application, she must understand the nature of the problem the application is designed to solve. Programming projects often begin with a relatively simple problem. These simply stated problems often mask a much more complicated issue. Rarely do programmers create applications …

This is a six-part introduction to database systems with a collected list of references at the end. These posts were derived from a set of papers I had to write for a business class.

1. Data Storage: An Evolution
2. RDBMS Introduction
3. Database Speak
4. Referential Integrity and Business Rules
5. Database Basics
6. Spreadsheets …

New information systems are not built in a vacuum. Systems analysts cannot hope to design and build an information system that meets the needs of an organization without first determining what those needs are. In order to collect requirements for a new information system, systems analysts must employee various data …

Intranets

Intranets are privately owned networks that operate like the public Internet in many respects. In most intranets, corporate users access company information via tools designed to run in web browsers. Intranets allow employees to share and access confidential corporate information. The benefit of these systems is that they operate …