488 private links
you could use IPv6 for the multicast addresses replacing 224.x.y.z with ff02::xyz or ff02::x:y:z etc.
Rather, the IPv6 multicast address for NTP is ff02::101. Likewise, the multicast IPv4 address for NTP is 224.0.1.1.
Reliable and free network scanner to analyze LAN. The program shows all network devices, gives you access to shared folders, provides remote control of computers (via RDP and Radmin), and can even remotely switch computers off. It is easy to use and runs as a portable edition. It should be the first choice for every network admin.
Daryl's Subnet Calculator
This document is designed to give the reader a reasonable working knowledge of TCP/IP subnetting, addressing, and routing. It is not intended to be complete, or to cover all issues. This is targeted toward LAN administrators just moving to TCP/IP, however it should help anyone who wants to know a little (more) about how TCP/IP works. This document does not, generally, apply to dial-up SLIP/PPP connections.
The difference between this (a primer) and an FAQ, is that most FAQ's, in practice, tend to be question-and-answer oriented, and generally seem to try to cover ALL issues, not just the ones frequently asked about. This primer is intended as a starting point for someone who has an interest in the subject, but doesn't know where to start or what questions to ask. This should also help to broaden the understanding of people who have worked with TCP/IP for a while, but either haven't had the time to study all the less-than-useful theory behind the subject, or have been somewhat overwhelmed by the many theoretical details and have missed the big picture.