Which three statements about implementing a NAT application layer gateway in a network are true?
(Choose three.)
A.
It allows client applications to use dynamic ports to communicate with a server regardless of
whether NAT is being used.
B.
It maintains granular security over application-specific data.
C.
It allows synchronization between multiple streams of data between two hosts.
D.
Application layer gateway is used only in VoIP/SIP deployments.
E.
Client applications require additional configuration to use an application layer gateway.
F.
An application layer gateway inspects only the first 64 bytes of a packet before forwarding it
through the network.
An application-level gateway (ALG), also known as an application-layer gateway, is an application
that translates the IP address information inside the payload of an application packet. An ALG is
used to interpret the application-layer protocol and perform firewall and Network Address
Translation (NAT) actions. These actions can be one or more of the following depending on your
configuration of the firewall and NAT:
Reference. http://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipaddr_nat/configuration/xe-
3s/asr1000/nat-xe-3s-asr1k-book/fw-msrpc-supp.html
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ALG offers:
1 .allowing client applications to use dynamic ephemeral TCP/ UDP ports to communicate with the known ports used by the server applications, even though a firewall configuration may allow only a limited number of known ports.
2 .converting the network layer address information found inside an application payload
3. synchronizing between multiple streams/sessions of data between two hosts exchanging data.
4. recognizing application-specific commands and offering granular security controls over them
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