Which protocol secures router management session traffic?

A.
SSTP

B.
POP

C.
Telnet

D.
SSH

Explanation:
http://www.cisco.com/en/US/tech/tk648/tk361/technologies_tech_note09186a0080120f48.shtml
Encrypting Management Sessions
Because information can be disclosed during an interactive management session, this traffic must
be encrypted so that a malicious user cannot gain access to the data being transmitted.
Encrypting the traffic allows a secure remote access connection to the device. If the traffic for a
management session is sent over the network in cleartext, an attacker can obtain sensitive
information about the device and the network. An administrator is able to establish an encrypted
and secure remote access management connection to a device by using the SSH or HTTPS
(Secure Hypertext Transfer Protocol) features. Cisco IOS software supports SSH version 1.0
(SSHv1), SSH version 2.0 (SSHv2), and HTTPS that uses Secure Sockets Layer (SSL) and
Transport Layer Security (TLS) for authentication and data encryption. Note that SSHv1 and
SSHv2 are not compatible.

Cisco IOS software also supports the Secure Copy Protocol (SCP), which allows an encrypted
and secure connection for copying device configurations or software images. SCP relies on SSH.
This example configuration enables SSH on a Cisco IOS device:
!
ip domain-name example.com
!
crypto key generate rsa modulus 2048
!
ip ssh time-out 60
ip ssh authentication-retries 3
ip ssh source-interface GigabitEthernet 0/1
!
line vty 0 4
transport input ssh
!