( )is a network entity that satisfies HTTP requests on the behalf of an origin Web server.
A. proxy server
B. local server
C. DNS server
D. Web server
查看答案
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.
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
微信支付 
支付宝支付