Question 78 of 2,015
VPN TechnologiesmediumMultiple ChoiceObjective-mapped

Quick Answer

The correct answer is that access-list 101 defines the traffic which will be encrypted, specifically protecting traffic from 192.168.10.0/24 to 192.168.20.0/24. This is because in a crypto map configuration interpretation for site-to-site IPsec, the match address command under the crypto map references an extended ACL that identifies "interesting traffic"—the only traffic that will be encrypted and sent through the IPsec tunnel to the peer. The ISAKMP policy and transform set define the encryption and hashing algorithms for phases 1 and 2, but without the ACL correctly matching the source and destination networks, no traffic is protected. On the ENCOR 350-401 exam, this concept tests your ability to read a crypto map configuration and distinguish between the roles of the ISAKMP policy, transform set, and the ACL; a common trap is confusing the ACL with a standard access list or thinking it controls routing rather than encryption. Remember the memory tip: "The ACL is the gatekeeper—only traffic it permits gets encrypted."

CCNP VPN Technologies Practice Question

This 350-401 practice question tests your understanding of vpn technologies. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.

Examine this configuration for a site-to-site VPN on a Cisco router:

crypto isakmp policy 10

encryption aes 256 hash sha256 authentication pre-share group 14 lifetime 86400 !

crypto ipsec transform-set TSET esp-aes 256 esp-sha256-hmac

mode tunnel !

crypto map CMAP 10 ipsec-isakmp

set peer 192.168.1.1 set transform-set TSET match address 101 !

interface GigabitEthernet0/0/0
 ip address 10.0.0.1 255.255.255.0
 crypto map CMAP

!

access-list 101 permit ip 192.168.10.0 0.0.0.255 192.168.20.0 0.0.0.255

Which statement about this configuration is true?

Question 1mediummultiple choice
Read the full VPN explanation →

Answer choices

Why each option matters

Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.

Correct answer & explanation

The access-list 101 defines the traffic that will be encrypted; traffic from 192.168.10.0/24 to 192.168.20.0/24 will be protected.

This is a classic crypto map-based site-to-site IPsec VPN. The ISAKMP policy defines phase 1 parameters, the transform set defines phase 2, and the crypto map binds them together with the peer and interesting traffic ACL. The ACL 101 specifies traffic from 192.168.10.0/24 to 192.168.20.0/24 to be encrypted.

Key principle: ACLs process entries top to bottom and stop at the first match. Entry order and interface direction matter as much as the permit or deny statement.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

  • The crypto map uses IKEv2 for key exchange because the transform set uses SHA-256.

    Why it's wrong here

    The 'crypto isakmp' commands indicate IKEv1, not IKEv2. IKEv2 uses 'crypto ikev2' commands.

  • The access-list 101 defines the traffic that will be encrypted; traffic from 192.168.10.0/24 to 192.168.20.0/24 will be protected.

    Why this is correct

    The 'match address 101' in the crypto map references ACL 101, which permits the specified source and destination networks. Only matching traffic triggers IPsec encryption.

    Related concept

    Standard ACLs match source addresses.

  • The ISAKMP policy lifetime of 86400 seconds is too long and will cause the tunnel to fail.

    Why it's wrong here

    The default ISAKMP lifetime is 86400 seconds (1 day), which is acceptable. It does not cause failure.

  • The crypto map should be applied to the tunnel interface, not the physical interface.

    Why it's wrong here

    Crypto maps are applied to physical interfaces (or subinterfaces) for site-to-site VPNs. Tunnel interfaces are used for VTI or DMVPN.

Common exam traps

Common exam trap: ACLs stop at the first match

ACLs are processed top to bottom. The first matching entry wins, and an implicit deny usually exists at the end.

Trap categories for this question

  • Command / output trap

    The 'crypto isakmp' commands indicate IKEv1, not IKEv2. IKEv2 uses 'crypto ikev2' commands.

Detailed technical explanation

How to think about this question

ACL questions test precision: source, destination, protocol, port and direction. A generally correct ACL can still fail if it is applied on the wrong interface or in the wrong direction.

KKey Concepts to Remember

  • Standard ACLs match source addresses.
  • Extended ACLs can match source, destination, protocol and ports.
  • The first matching ACL entry is used.
  • There is usually an implicit deny at the end.

TExam Day Tips

  • Check inbound versus outbound direction.
  • Read the ACL from top to bottom.
  • Look for a broader permit or deny above the intended line.

Key takeaway

ACLs process entries top to bottom and stop at the first match. Entry order and interface direction matter as much as the permit or deny statement.

Real-world example

How this comes up in practice

A security administrator must allow nursing staff to reach a patient records server while blocking access from the guest Wi-Fi VLAN. After applying an extended ACL, traffic is still blocked from nursing workstations. The ACL was applied outbound instead of inbound on the wrong interface. Questions like this test ACL direction and placement rules.

What to study next

Got this wrong? Here's your next step.

Review ACL processing order, placement rules (standard near destination, extended near source), and inbound vs outbound direction. Study wildcard masks and implicit deny. Then practise related 350-401 ACL questions on filtering logic and placement.

Related practice questions

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FAQ

Questions learners often ask

What does this 350-401 question test?

VPN Technologies — This question tests VPN Technologies — Standard ACLs match source addresses..

What is the correct answer to this question?

The correct answer is: The access-list 101 defines the traffic that will be encrypted; traffic from 192.168.10.0/24 to 192.168.20.0/24 will be protected. — This is a classic crypto map-based site-to-site IPsec VPN. The ISAKMP policy defines phase 1 parameters, the transform set defines phase 2, and the crypto map binds them together with the peer and interesting traffic ACL. The ACL 101 specifies traffic from 192.168.10.0/24 to 192.168.20.0/24 to be encrypted.

What should I do if I get this 350-401 question wrong?

Review ACL processing order, placement rules (standard near destination, extended near source), and inbound vs outbound direction. Study wildcard masks and implicit deny. Then practise related 350-401 ACL questions on filtering logic and placement.

What is the key concept behind this question?

Standard ACLs match source addresses.

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Last reviewed: Jun 18, 2026

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