Discuss the potential advantages and drawbacks in the use of an X.500 directory service in place
of DNS and the Internet mail delivery programs. Sketch the design of a mail delivery system for
an internetwork in which all mail users and mail hosts are registered in an X.500 database.
What will be an ideal response?
For access to conventional email addresses (based on Internet Domain Names), X.500 would provide a similar
facilities to the DNS service. X.500 is designed to be scalable. If this is achieved in practice, then it should
meet the future needs of large-scale networking better than DNS.
The main advantage of X.500 is that it is an attribute-based directory service. In principle, users could address
messages to people by quoting their real names and their organisational affiliations, instead of the Domain
Name based addresses currently used. The mail system would make a search request of X.500 to find the
corresponding DNS or other network address of the user’s mailbox. A drawback is that searching with a wide
scope is quite slow and costly in computing resources, the scope could be limited by the use of the
organisational affiliation. Several alternate mailboxes could be held in the directory server, providing fault
tolerant mail delivery.
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Adapt the central server algorithm for mutual exclusion to handle the crash failure of any client (in any state), assuming that the server is correct and given a reliable failure detector. Comment on whether the resultant system is fault tolerant. What would happen if a client that possesses the token is wrongly suspected to have failed?
What will be an ideal response?
For your profile picture, you can upload picture files up to ________ MB in size, in the JPG, GIF, or PNG formats
A) 2 B) 3 C) 4 D) 5
You can create a blank presentation or a presentation with a theme.
Answer the following statement true (T) or false (F)
On single-processor systems, the operating system uses________to divide processor time among the many processes.
a) process slicing. b) time slicing. c) time splitting. d) None of the above