ICND1 WAN Technologies & Network Security 4 — Questions and Answers
Question 1: What is the default encapsulation type on a Cisco serial interface connected to another Cisco router?
- Frame Relay
- PPP
- HDLC (Correct answer)
- SLIP
Correct answer: HDLC
Cisco uses its own variation of HDLC (High-Level Data Link Control) as the default serial encapsulation.
Question 2: An administrator applies an ACL outbound on an interface. Which traffic does this ACL evaluate?
- Traffic entering the router on that interface
- Traffic leaving the router through that interface (Correct answer)
- All traffic passing through the router
- Only traffic destined for the router itself
Correct answer: Traffic leaving the router through that interface
An outbound ACL evaluates packets after the routing decision is made, as they exit the specified interface.
Question 3: Which WAN technology uses 23 B-channels and 1 D-channel in its PRI (Primary Rate Interface) configuration in North America?
- DSL
- Frame Relay
- ISDN (Correct answer)
- ATM
Correct answer: ISDN
ISDN PRI in North America provides 23 bearer (B) channels at 64 Kbps each plus one 64 Kbps delta (D) channel for signaling.
Question 4: When configuring a site-to-site IPsec VPN, what is the purpose of IKE Phase 1?
- To encrypt the actual data payload
- To establish a secure management channel (ISAKMP SA) for IKE Phase 2 negotiation (Correct answer)
- To define which traffic is interesting and should be encrypted
- To assign IP addresses to VPN clients
Correct answer: To establish a secure management channel (ISAKMP SA) for IKE Phase 2 negotiation
IKE Phase 1 creates the ISAKMP Security Association, a secure authenticated channel used to negotiate the IPsec SA in Phase 2.
Question 5: Which command correctly configures a named extended ACL on a Cisco router?
- access-list 101 permit tcp 192.168.1.0 0.0.0.255 any eq 80
- ip access-list extended WEBTRAFFIC (Correct answer)
- access-list WEBTRAFFIC extended permit tcp any any eq 80
- ip access-list 101 extended permit tcp any any
Correct answer: ip access-list extended WEBTRAFFIC
'ip access-list extended NAME' creates a named extended ACL in ACL configuration mode.
Question 6: What does CIR (Committed Information Rate) represent in a Frame Relay network?
- The maximum possible burst speed on the WAN link
- The minimum guaranteed bandwidth the provider will deliver on a PVC (Correct answer)
- The speed of the local access loop to the Frame Relay switch
- The total bandwidth shared across all PVCs
Correct answer: The minimum guaranteed bandwidth the provider will deliver on a PVC
CIR is the guaranteed minimum bandwidth that the service provider commits to delivering on a Frame Relay PVC.
Question 7: A network administrator wants to prevent IP address spoofing on an interface by blocking packets with source addresses from RFC 1918 private ranges arriving on the outside interface. This is an example of which security technique?
- Reflexive ACLs
- Dynamic ACLs
- Ingress filtering (Correct answer)
- Port security
Correct answer: Ingress filtering
Ingress filtering blocks packets arriving from the internet with private or internal source IP addresses, preventing spoofing attacks.
ICND1 WAN Technologies & Network Security 4
What is the default encapsulation type on a Cisco serial interface connected to another Cisco router?