The term folksonomy refers to the process whereby a group of people collaborate to organize information using an impromptu vocabulary.
A common example in the corporate world is team building excercises, whereby a group of individuals rearrange flash cards on the floor or stickers on a white board. By getting a large group of people’s input, you have a higher probability of getting an appropriate classification of the information in question.
other apps (e.g., file transfer, telnet) require 100% reliable data transfer
some apps (e.g., Internet telephony, interactive games) require low delay to be “effective”
some apps (e.g., multimedia) require minimum amount of bandwidth to be “effective”
other apps (“elastic apps”) make use of whatever bandwidth they get
Transport service requirements of common apps Application file transfer e-mail Web documents real-time audio/video stored audio/video interactive games instant messaging Data loss no loss no loss no loss loss-tolerant loss-tolerant loss-tolerant no loss Bandwidth elastic elastic elastic audio: 5kbps-1Mbps video:10kbps-5Mbps same as above few kbps up elastic Time Sensitive no no no yes, 100’s msec yes, few secs yes, 100’s msec yes and no
contacted by local name server that can not resolve name
root name server:
contacts authoritative name server if name mapping not known
returns mapping to local name server
13 root name servers worldwide b USC-ISI Marina del Rey, CA l ICANN Marina del Rey, CA e NASA Mt View, CA f Internet Software C. Palo Alto, CA i NORDUnet Stockholm k RIPE London m WIDE Tokyo a NSI Herndon, VA c PSInet Herndon, VA d U Maryland College Park, MD g DISA Vienna, VA h ARL Aberdeen, MD j NSI (TBD) Herndon, VA
puts burden of name resolution on contacted name server
contacted server replies with name of server to contact
“ I don’t know this name, but ask this server”
requesting host surf.eurecom.fr gaia.cs.umass.edu root name server 1 2 3 4 5 6 authoritative name server dns.cs.umass.edu 7 8 iterated query local name server dns.eurecom.fr intermediate name server dns.umass.edu
Domain name : tells the domain to which this record applies.
Time_to_live: field gives an indication of how stable the record is. Information that is highly stable is assigned large value such as 86400. Information that is highly volatile is assigned a smaller value as 60.
Class: field is always IN for internet information. For non-internet information, other codes can be used.