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Domain Name Space | Hierachical Name Space

Domain Name System (or Service or Server): ØWhen DNS was not into existence, one had to download a Host file containing host names and their corresponding IP address. ØBut with increase in number of hosts of internet, the size of host file also increased. ØThis resulted in increased traffic on downloading this file. To solve this problem the DNS system was introduced. ØIt is an internet service that translates domain names into IP addresses. ØBecause domain names are alphabetic, they're easier to remember. ØThe Internet however, is really based on IP addresses. ØEvery time you use a domain name, therefore, a DNS service must translate the name into the corresponding IP address. ØFor example, the domain name www.example.com might translate to 198.105.232.4. ØIt uses a hierarchical naming scheme and distributed database of IP addresses and associated names. ØIf one DNS server doesn't know how to translate a particular domain name, it asks another one, and so on, until the correct IP…

Domain Name System Architecture

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Domain Name System Architecture: ØThe Domain name system comprises of Domain Names, Domain Name Space, Name Server that have been described below: a)Domain Names: ØDomain Name is a symbolic string associated with an IP address. ØEach node in the tree has a domain name. ØA full domain name is a sequence of labels separated by dots (.). ØThe domain names are alwaysread from the node up to the root. ØThe last label is the label of the root (null). This means that a full domain name always ends in a null label, which means the last character is a dot because the null string is nothing.


Fully Qualified Domain Name ØIf a label is terminated by a null string [null means nothing, the label ends with a dot (.) ] , it is called a fully qualified domain name.(FQDN). ØAn FQDN is a domain name that contains the full name of a host.

Types of Automata Machines

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Types of Finite State Machine:
Acceptors: ·Also called recognizer and sequence detectors, which produce binary output, indicating whether or not the received input is accepted. ·Each state of an acceptor is either "Accepting state “or "Rejecting state". ·The languages which are accepted by acceptor are called regular languages. ·Once all input has been received by machine, if the current state is an accepting state, it means that the input is accepted; otherwise it is rejected.

Transducers: ·Transducers generate output based on a given input and/or a state using actions. ·In these machines output is associated with input. 
Generators:

Formal Definition of Automata | FSM | 5-Tuple Machine

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ØAn automaton is Quintuple or 5-tuple machine. ØIt is represented by
M= (Q, ∑, δ, q0, F), where − ·Q is a finite set of states. · is a finite set of symbols, called the  inputalphabet of the automaton. ·δ is the transition function/mapping function which maps Q x ∑ à Q(Here x is Cartesian Product) Above mapping is usually represented by 1.Transition function/Mapping function 2.Transition diagram / Transition graph / Transition State diagram/ State diagram 3.Transition table/Transition state table/Mapping table ·q0 is the initial state from where any input is processed (q0∈ Q). ·F is a set of final state/states of Q (F ⊆ Q). ØExample of lift control: