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David Cao

David is a Cloud & DevOps Enthusiast. He has years of experience as a Linux engineer. He had working experience in AMD, EMC. He likes Linux, Python, bash, and more. He is a technical blogger and a Software Engineer. He enjoys sharing his learning and contributing to open-source.

The SSL: SSLV3_ALERT_CERTIFICATE_EXPIRED error suggests that the SSL certificate used by the server you’re trying to connect to has expired. The best and most secure solution is to update the expired certificate with a new, valid one. This usually involves generating a new certificate and configuring the server to use it. If you don’t control …

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A subnet, or subnetwork, is a logical subdivision of an IP network. It’s essentially a smaller network within a larger network, created by dividing the network address space into smaller segments. This division is achieved through a process called subnetting. By dividing the network into smaller segments, subnet allows for more efficient management of network …

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“Practical Linux System Administration” by Kenneth emerges as a remarkably comprehensive guide for anyone aspiring to master the intricacies of Linux administration. This book is a treasure trove of practical knowledge, seamlessly blending fundamental concepts with advanced techniques. From the outset, Kenneth’s expertise shines through. He meticulously introduces the Linux operating system, making it approachable …

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In today’s data-driven environment, Excel’s XLOOKUP function is a game-changer, particularly for performing lookups across different worksheets and even different workbooks. This versatility allows for more integrated and complex data analysis. Let’s dive into how you can effectively use XLOOKUP for cross-worksheet and cross-workbook lookups. Understanding XLOOKUP for Cross-Worksheet Lookups Cross-worksheet lookups are essential when …

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The search_mode parameter in the XLOOKUP function in Microsoft Excel specifies the direction or method Excel should use when searching for the lookup_value. This parameter can greatly affect how the function operates, especially in large datasets or specific search scenarios. Here’s a detailed explanation of each option within the search_mode parameter, along with examples. Introduction …

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The XLOOKUP function in Excel is powerful, but like any tool, it can occasionally yield errors. Understanding these common issues and knowing how to resolve them is crucial for efficient use of XLOOKUP. Here are some of the frequent errors encountered with XLOOKUP and strategies to fix them: 1. #N/A Error: Value Not Found Cause: …

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