21 - Questions - WAN Technologies

Which wired broadband internet access technology option uses twisted-pair telephone lines for transport?

ADSL

Which two options are site-to-site VPN options? (Choose two.)

DMVPN IPsec

Which optical technology provides highest data rates?

DWDM

Which statement about site-to-site VPN deployment mode is true?

In a site-to-site VPN, a tunnel is built between VPN gateways present at each of the sites.

Which two statements about provider-managed VPNs are true? (Choose two.)

Provider-managed Layer 3 MPLS VPNs make the provider's network appear as a router for each connected customer. Provider-managed Layer 2 MPLS VPNs make remote customer sites appear as directly connected.

Which statement about WAN connections is true?

The correct answer is "The VPN technology makes the internet an inexpensive and secure option for connecting to remote offices." Only internet-based connections are using the public infrastructure, other WAN options are utilizing private service provider networks. WAN service provider can have one network interconnecting all enterprise's locations or it can interconnect with other providers to ensure the required geographic coverage. The access technology of one provider may differ from the access technology of another, and yet another technology may be employed on providers' interlinks. The ATM is a packet-switched technology, and not circuit-switched.

Which statement about VPLS is true?

The correct answer is "VPLS is an MPLS-based VPN." The underlying technology that implements VPLS is MPLS and it is provider managed and not under the control of an enterprise. Unlike IPsec-based VPNs, VPLS itself does not implement cryptographic functions. VPLS is a Layer 2 VPN where the provider's network behaves as a huge switch that connects enterprise remote locations.

Which medium is used by service providers to transmit data over WAN connections with SONET or SDH?

The correct answer is "fiber optic." Provider's networks are mostly built of high-bandwidth fiber-optic media, using either the SONET or SDH standard.

When establishing a VPN tunnel in site-to-site deployment, the VPN tunnel is established between which two end-points?

The correct answer is "local and remote VPN gateway devices." In site-to-site VPN deployment, the end-device (for example, the individual host) is not establishing the tunnel. The tunnel is established between edge devices at remote locations.

Which statement regarding WAN topologies is true?

The correct answer is: "WAN point-to-point connections are such that remote devices seem to be on the same physical segment." Point-to-point topology establishes a circuit (a logical connection) between exactly two sites. It is also called a Layer 2 service as it creates a connection, via which it seems that both sites are on the same physical segment.

Which three statements about WAN devices are true? (Choose three.)

The correct answers are: "A DSL modem is a DCE device," "A router is connected to the DSU component of the CSU/DSU device," and "A fiber converter can be part of the CPE." A modem is always a DCE device, even when it is a module in a DTE device. A fiber converter is used to connect to the provider's fiber circuit, therefore it is a DCE and not the DTE devices. CSU/DSU devices are used when communication over digital and not analog lines. Modems are used with analog lines. As any other DCE, a fiber converter can be owned and managed by the enterprise, hence part of customers premises equipment. It can also be leased from the provider, for example, not owned, and managed by the provider.

Match the VPN term with its correct description.

The correct answers are: IPSec VPN is a cryptographic VPN; SSL enabled browser is a client in remote-access VPN; Firewall is a device that can act as VPN gateway, to terminate VPNs; Cisco DMVPN is a site-to-site VPN solution that implements hub-and-spoke topology and facilitates establishment of direct spoke-to-spoke connections; and GRE over IPSec VPN is a site-to-site VPN solution that enables secure exchange of broadcast and multicast traffic. VPNs are not necessarily cryptographic. By employing IPSec framework when establishing a VPN connection, cryptographic functions of IPSec are added and the VPN is called a cryptographic VPN. IPSec does not support broadcast and multicast traffic and that is why additional encapsulation using GRE protocol is added. GRE over IPSec enables secure exchange of broadcast and multicast traffic. In a remote-access deployment, one side of VPN is a VPN gateway, which can be a firewall, and the other side is an individual host. The host requires specialized software (acting as a VPN client) to establish a VPN connection. SSL enabled browser is an example of such software. Cisco DMVPN is a solution that first builds a hub-and-spoke VPN connection topology, then uses it to create spoke-to-spoke connections when required.

Which two statements about VPNs are true? (Choose two.)

VPNs do not necessarily implement cryptographic functions. VPNs can be built using the technology used within the service provider WAN.

Which statement regarding WANs is true?

WANs use services of carriers that manage large networks, which can be based on different technologies, such as telephony, cable, satellite and others.

Match each WAN device to its function.

converts digital signals for sending over analog circuits modem used in LANs to provide ports that interface to WANs router part of the service provider network and used in "building" a WAN core router provides a digital interface for DTE to connect to digital WAN circuits CSU/DSU

Which of the basic ISP connectivity types provides the highest redundancy?

dual-multihomed

Which three options are classified as internet-based WAN connectivity options? (Choose three.)

xDSL cable 4G cellular