Time to live For the 1969 French film, see Time to Live (film) . Time to live ( TTL ) or hop limit is a mechanism which limits the lifespan or lifetime of data in a computer or network. TTL may be implemented as a counter or timestamp attached to or embedded in the data. Once the prescribed event count or timespan has elapsed, data is discarded or revalidated. In computer networking , TTL prevents a data packet from circulating indefinitely. In computing applications, TTL is commonly used to improve the performance and manage the caching of data. IP packets Under the Internet Protocol , TTL is an 8-bit field. In the IPv4 header , TTL is the 9th octet of 20. In the IPv6 header , it is the 8th octet of 40. The maximum TTL value is 255, the maximum value of a single octet. A recommended initial value is 64. [1] [2] The time-to-live value can be thought of as an upper bound on the time that an IP datagram can exist in an Internet system. The TTL field is set by the send
A short dipole is a simple wire antenna. One end of it is open-circuited and the other end is fed with AC source. This dipole got its name because of its length. Frequency range The range of frequency in which short dipole operates is around 3KHz to 30MHz. This is mostly used in low frequency receivers. Construction & Working of Short Dipole The Short dipole is the dipole antenna having the length of its wire shorter than the wavelength. A voltage source is connected at one end while a dipole shape is made, i.e., the lines are terminated at the other end. The circuit diagram of a short dipole with length L is shown. The actual size of the antenna does not matter. The wire that leads to the antenna must be less than one-tenth of the wavelength. That is L < λ 10 L < λ 10 Where L is the length of the wire of the short dipole. λ is the wavelength. Another type of short dipole is infinitesimal dipole, whose length is far less than its wave length. Its constructiion is simila
There are 141 ebook available on this link , https://drive.google.com/drive/mobile/folders/1-o85zbr20F1W1aCrxBhfgjRanQhYJv6F For Electronics Engineering As for as Communication Control system Signal system Digital EDC Math EMT Network Theory For Electronics Engineering As for as Communication Control system Signal system Digital EDC Math EMT Network Theory
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