Address Mapping:  Ø The  delivery of a packet to a host or router requires two levels of addressing: Logical and physical. Ø    We need to map logical address to its corresponding physical address and vice versa. Ø    This can be done by  Static mapping and Dynamic mapping. Ø    Static mapping  involves in the  creation of a table that associates a logical address with a physical address.  This address mapping table is  stored in each device  on the network. Ø    Static mapping has some limitations because physical addresses may change in the following ways: ·       A machine could  change its Network Interface Card (NIC)  , which results in a new MAC address. ·        In some Local Area Networks(LAN), such as  Local Talk, the MAC address changes every time the computer is turned on. ·    ...

Domain Name System Architecture: Ø   The Domain name system comprises of Domain Names, Domain Name Space, Name Server that have been described below: a)     Domain Names:   Ø   Domain Name is a symbolic string associated with an IP address . Ø   Each node in the tree has a domain name. Ø   A full domain name is a sequence of labels separated by dots (.). Ø   The domain names are always read from the node up to the root . Ø   The 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 Ø   If 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). Ø   An FQDN is a domain name that contains the full name of a host. Ø   It...

Application Layer Services A.         Directory Services Ø   These services are mapping between name and its value , which can be variable value or fixed. Ø   This software system helps to store the information, organize it, and provides various means of accessing it. a)     Accounting: ·    In an organization, a number of users have their user names and passwords mapped to them. ·       Directory Services provide means of storing this information in cryptic form and make available when requested b)     Authentication & Authorization: ·     User credentials are checked to authenticate a user at the time of login and/or periodically . ·       User accounts can be set into hierarchical structure and their access to resources can be controlled using authorization schemes. c)      Domain Nam...