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TCP Window Size – Quick Primer


The TCP window size is basically the method employed by the receiving client/host to inform the sender, what the current buffer size should be for all the data within that connection.  It’s a flow control system which ensure that the receiving host doesn’t get overloaded with data, it’s very important that this is a dynamic…

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Some IP Routing Stuff


Conceptually IP routing is pretty straight forward, especially when you look at it from the hosts point of view.  If the destination is directly connected such as a direct link or on the same Ethernet network then the IP datagram is simply forwarded to it’s destination.  If it’s not connected then the host simply send…

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The TCP Keepalive Timer


If you’re new to the world of TCP/IP, you may be quite confused to hear that no data at all flows across an idle TCP connection.  Just to clarify, if no process on either side of the connection is sending data then nothing at all will be exchanged by the 2 TCP modules.  Many networking…

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The Basics of the Domain Name System


So what is the Domain Name System or as it’s more commonly known as DNS? Well, very simply it is a huge distributed database which contains the domain names and addresses of all devices on the network.  This structure is crucial to the way DNS functions, it allows local control of specific segments – and…

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TCP/IP Congestion Avoidance Algorithm


Lost packets is one of the biggest difficulties for any transport protocol.  Sending data across a variety of platforms, switches, hubs and routers is bound to end up with some lost data.  Every protocol therefore needs a way of dealing with these lost packets.   The congestion avoidance algorithm is one way of dealing with…

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Defining an Internet Address


Absolutely every device that exists on the internet needs an IP address (some call it an internet address). There are no exceptions – every pc, laptop, phone, coffee machine or printer if it’s online and accessible it needs an IP address. Needless to say the internet facing ones have to be unique in order to…

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A Little Bit About IP Checksums


The role of checksums in IP headers is actually very important.  THey are used to make sure that data is not corrupted during it’s journey from the source address to the destination.  TCP/IP uses a specific algorithm to check the data which involves dividing the checksum data in separate 16 bit fields.  Every one of…

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