Ccna certification Practice Tests

363

 55.  A.  Turning on password complexity would reduce the risk of a password attack. Password 

expiration would be secondary to password complexity to reduce the risk, since without 

complexity the user could create a simple password. Phishing protection would not prevent 

a password attack. Time restrictions would not prevent a password attack.

 56.  D.  Generic Routing Encapsulation (GRE) tunnels provide packet-in-packet encapsulation. 

It takes the original IP packet and encapsulates it, adding another IP packet for the 

GRE tunnel. GRE tunnels alone do not provide any encryption. GRE does not use IPsec 

security by default. It must be configured to use this security protocol inside of the 

GRE packet; this is commonly called an IPsec security transform. GRE uses a layer 3 IP 

protocol of 47, not 57. GRE does not provide per-packet authentication; IPsec can provide 

this service.

 57.  A.  Generic Routing Encapsulation (GRE) is a Cisco proprietary standard for 

encapsulating layer 3 protocols over an IP network, such as the Internet. Point-to-Point 

Protocol (PPP) is an IEEE standardized protocol for point-to-point links. IP Security 

(IPsec) is an IEEE standardized protocol for encryption of IP packets. Secure Sockets 

Layer (SSL) is an IEEE standardized protocol for mutual authentication and encryption 

between two hosts using certificates.

 58.  C.  GRE uses the layer 3 protocol 47, which is the protocol that is stated in the layer 3 

header. These protocol numbers are IP layer protocol numbers and should not be confused 

with TCP/UDP layer 4 port numbers. All of the other options are incorrect.

 59.  C.  The network is unrouteable, since interface G0/1 on Router A is configured 

with a 192.168.1.0/24 network and interface G0/1 on Router B is configured with a 

192.168.1.0/24. The route statement that needs to be configured will not pass any traffic 

since 192.168.1.0/24 is directly configured on both routers. The destination on Router A 

of the tunnel is correct, but the interface G0/1 on Router B is incorrectly addressed. The 

serial interfaces are on different addresses but most likely correspond to the IP network in 

the WAN cloud.

 60.  D.  The correct route statement is 

ip route 192.168.3.0 255.255.255.0 

192.168.2.2, because the network of 192.168.2.0/24 is built between these two routers. 

The tunnel acts as a routed interface between the routers. The route statement 

ip route 

192.168.3.0 255.255.255.0 tunnel 0 is incorrect. The route statement ip route 

192.168.2.0 255.255.255.0 tunnel 0 is incorrect. The route statement  

ip route 192.168.3.0 255.255.255.0 serial 0/0/1 is incorrect.

 61.  A.  The maximum transmission unit of a GRE tunnel is 1476 because there are 24 bytes 

of overhead for the GRE header; 20 bytes are used by the public IP header and 4 bytes 

are used for GRE. Ethernet is commonly set to an MTU of 1492 or an MTU of 1500. 

An 802.1Q packet is commonly set to an MTU of 1528 because of the additional VLAN 

tagging information.

 62.  B.  The command 

show interface tunnel 0 will show in the output the source and 

destination of the tunnel. The command 

show ip tunnel 0 is incorrect. The command 

show ip gre is incorrect. The command show ip route is incorrect.

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