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Showing posts from May, 2015

Loopback, Private and Public IP Addresses

Loopback Address Loopback IP address from 127.0.0.1 to 127.255.255.254? Private Address The private address space specified in RFC 1918 is defined by the following three address blocks: 10.0.0.0/8 The 10.0.0.0/8 private network is a class A network ID that allows the following range of valid IP addresses: 10.0.0.1 to 10.255.255.254. The 10.0.0.0/8 private network has 24 host bits that can be used for any subnetting scheme within the private organization. 172.16.0.0/12 The 172.16.0.0/12 private network can be interpreted either as a block of 16 class B network IDs or as a 20-bit assignable address space (20 host bits) that can be used for any subnetting scheme within the private organization. The 172.16.0.0/12 private network allows the following range of valid IP addresses: 172.16.0.1 to 172.31.255.254. 192.168.0.0/16 The 192.168.0.0/16 private network can be interpreted either as a block of 256 class C network IDs or as a 16-bit assignable address space (16 host bits)

Hadoop Story

How did Hadoop get here? As the World Wide Web grew at a dizzying pace in the late 1900s and early 2000s, search engines and indexes were created to help people find relevant information amid all of that text-based content. During the early years, search results were returned by humans. It’s true! But as the number of web pages grew from dozens to millions, automation was required. Web crawlers were created, many as university-led research projects, and search engine startups took off (Yahoo, AltaVista, etc.). One such project was Nutch – an open-source web search engine – and the brainchild of Doug Cutting and Mike Cafarella. Their goal was to invent a way to return web search results faster by distributing data and calculations across different computers so multiple tasks could be accomplished simultaneously. Also during this time, another search engine project called Google was in progress. It was based on the same concept – storing and processing data in a distributed, automa