In the following four options about web cache, which one is not correct?( )
A web cache is both a server and a client at the same time.
B. A web cache is purchased and installed by an ISP.
C. A web cache can raise the response time for a client request.
D. A web cache can reduce traffic on an institution’s access link to the Internet.
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FTP uses two parallel connections to transfer a file, they are ( ).
A. TCP and UDP connection
B. connection with pipelining and without pipelining
C. control an data connection
D. client-server and browser-server connection
In the following four services, which one can not provide by DNS?( )
A. Host aliasing
B. Mail server aliasing
C. translate hostname to IP addresses
D. translate MAC addresses to IP addresses
There are three classes of DNS servers, there are ( ).
A. root DNS server, top-level domain DNS server and local DNS server
B. root DNS server, top-level domain DNS server and authoritative DNS server
C. root DNS server, local DNS server and authoritative DNS server
D. root DNS server, local DNS server and top-level domain DNS server
In HTTP request message, the entity body is empty with the ( )method, but is used with the ( )method.
A. GET, POST
B. POST,GET
C. GET, HEAD
D. POST, HEAD
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