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- Which protocol in the IPsec suite provides data integrity and authentication but not confidentiality?
a. Authentication Header (AH)
b. Encapsulating Security Payload (ESP)
c. Transport Layer Security (TLS)
d. Secure Sockets Layer (SSL)
Answer: a. Authentication Header (AH)notes.networklessons+2 - In which two modes can the Authentication Header (AH) protocol operate?
a. Stream and Block
b. Transport and Tunnel
c. Static and Dynamic
d. Session and Datagram
Answer: b. Transport and Tunnelgeeksforgeeks+2 - What is the primary function of the Authentication Header (AH) in networking?
a. Encryption only
b. Authentication and integrity
c. Key exchange
d. Data fragmentation
Answer: b. Authentication and integritylogsign+2 - Which feature does AH not provide?
a. Data authenticity
b. Data confidentiality
c. Data integrity
d. Anti-replay protection
Answer: b. Data confidentialityreddit+2 - Which field in the AH is used to mitigate replay attacks?
a. Time stamp
b. Sequence number
c. Source address
d. Destination address
Answer: b. Sequence numberexamtopics+2 - What type of cryptographic operation is used by AH for authentication?
a. Hashing
b. Symmetric encryption
c. Asymmetric encryption
d. Compression
Answer: a. Hashingibm+2 - AH is ineffective when used with which network function because it modifies packet headers?
a. Routing
b. NAT (Network Address Translation)
c. Fragmentation
d. Switching
Answer: b. NAT (Network Address Translation)sciencedirect+2 - What does AH authenticate in transport mode?
a. The new IP header only
b. The entire inner IP packet and payload
c. The IP payload and parts of the IP header
d. Only the payload
Answer: c. The IP payload and parts of the IP headertutorialspoint+2 - What does AH authenticate in tunnel mode?
a. The new outer IP header only
b. Only TCP/UDP headers
c. The entire original IP packet
d. The destination field only
Answer: c. The entire original IP packetnotes.networklessons+2 - Which IP header fields are NOT protected by AH due to their mutable nature?
a. Source and Destination Address
b. Time to Live (TTL) and Header Checksum
c. Protocol and Version
d. Padding and Options
Answer: b. Time to Live (TTL) and Header Checksumgeeksforgeeks+2 - Which protocol provides similar functionality to AH but also supports encryption?
a. Internet Key Exchange (IKE)
b. Encapsulating Security Payload (ESP)
c. Secure Copy Protocol (SCP)
d. Simple Network Management Protocol (SNMP)
Answer: b. Encapsulating Security Payload (ESP)scribd+2 - In IPsec, what is typically used to generate the authentication value in AH?
a. DES Encryption
b. Diffie-Hellman key exchange
c. HMAC with MD5 or SHA algorithms
d. Plain text comparison
Answer: c. HMAC with MD5 or SHA algorithmsibm+1 - Which service is NOT provided by the Authentication Header (AH)?
a. Data origin authentication
b. Confidentiality
c. Integrity
d. Replay protection
Answer: b. Confidentialityexamtopics+2 - With AH, what happens if packet authentication fails?
a. Packet is queued
b. Packet is delivered with a warning
c. Packet is discarded
d. Packet is encrypted
Answer: c. Packet is discardedtutorialspoint+1 - Which field in the AH identifies the security protocol used?
a. Protocol
b. Next Header
c. Sequence Number
d. Authentication Data
Answer: b. Next Headertutorialspoint - If the mutable fields of an IP header are changed in transit, what does AH do?
a. Drops the packet only in tunnel mode
b. Ignores the changes for those fields
c. Recalculates the hash on arrival
d. Requests retransmission
Answer: b. Ignores the changes for those fieldstutorialspoint - Which layer of the OSI model does AH primarily operate at?
a. Physical layer
b. Data link layer
c. Network layer
d. Transport layer
Answer: c. Network layerlogsign+2 - What is required to generate the authentication hash in AH?
a. Secret key shared between peers
b. Random number
c. Public certificate
d. MAC address
Answer: a. Secret key shared between peersnotes.networklessons+2 - When AH is enabled, which part of the packet can still be read by an eavesdropper?
a. Only the hash value
b. Entire payload
c. Source and destination address
d. Payload and non-mutable header fields
Answer: d. Payload and non-mutable header fieldsibm+2 - Which IPsec protocol is more commonly used in practice for VPNs?
a. AH
b. ESP
c. Both are equally common
d. Neither is used for VPNs
Answer: b. ESPnotes.networklessons+2 - What is the main disadvantage of using AH with NAT devices?
a. It requires extra bandwidth
b. NAT alters IP headers, breaking the integrity check
c. NAT requires encryption
d. NAT performs hashing
Answer: b. NAT alters IP headers, breaking the integrity checkibm+2 - Which field in the AH is optional but used for authentication data?
a. Padding
b. Authentication Data
c. Reserved
d. Key Data
Answer: b. Authentication Datatutorialspoint - Who defines the structure and deployment of AH?
a. ISO
b. IETF in RFC 4302
c. IEEE
d. W3C
Answer: b. IETF in RFC 4302sciencedirect+2 - Which of the following statements is TRUE regarding AH in IPv6?
a. Only works with IPv4
b. Is deprecated in IPv6
c. Can be used for integrity/authentication in IPv6
d. Can encrypt IPv6 payloads
Answer: c. Can be used for integrity/authentication in IPv6cloudflare+2 - The main purpose of using AH in tunneling mode is to:
a. Secure the payload only
b. Authenticate the inner and outer IP headers along with payload
c. Load balance packets
d. Increase routing performance
Answer: b. Authenticate the inner and outer IP headers along with payloadgeeksforgeeks+2 - Why is ESP often preferred to AH in corporate VPN deployments?
a. ESP is easier to configure
b. ESP supports confidentiality (encryption)
c. AH is less secure
d. AH is slower
Answer: b. ESP supports confidentiality (encryption)notes.networklessons+2 - Which additional protection determines if the packet was delayed or replayed in AH?
a. Hash value
b. Sequence number
c. SPI value
d. Header checksum
Answer: b. Sequence numberexamtopics+2 - What does the Security Parameters Index (SPI) field in AH indicate?
a. Number of packets
b. Identifies the security association
c. Destination IP address
d. Packet sequence
Answer: b. Identifies the security associationsciencedirect+1 - When is AH processing applied to a packet?
a. Always, regardless of fragmentation
b. Only to non-fragmented packets
c. After encryption
d. Only during routing
Answer: b. Only to non-fragmented packetstutorialspoint - What is the relationship between AH and connection orientation?
a. AH is connectionless
b. AH is connection-oriented
c. AH works only with TCP
d. AH requires persistent sessions
Answer: a. AH is connectionlessgeeksforgeeks+1 - Which algorithm may be used for the AH’s HMAC computations, as per RFCs?
a. RC4
b. SHA-1 or SHA-256
c. DES
d. AES-GCM
Answer: b. SHA-1 or SHA-256ibm+1 - How does AH help prevent packet alteration attacks?
a. By providing replay protection
b. By authenticating headers and payload
c. By encrypting the payload
d. By compressing the packet
Answer: b. By authenticating headers and payloadcloudflare+2 - Which field would you expect to find in the Authentication Header?
a. New Protocol Data Unit
b. Authentication Data
c. Routing Table ID
d. NAT-T Flag
Answer: b. Authentication Datageeksforgeeks+1 - What happens if a packet’s sequence number is outside the acceptance window in AH?
a. It is queued until valid
b. It is accepted with a flag
c. It is rejected/discarded
d. Sender is requested to resend
Answer: c. It is rejected/discardedgeeksforgeeks - What does the Next Header field in the AH indicate?
a. The next protocol header following the AH
b. The last IP address in routing
c. End of packet
d. Routing header
Answer: a. The next protocol header following the AHtutorialspoint - Which statement best describes AH’s defense against denial-of-service attacks?
a. Prevents all types of DoS
b. Reduces chance by discarding unauthenticated packets
c. Encrypts all incoming packets
d. Diverts attack traffic automatically
Answer: b. Reduces chance by discarding unauthenticated packetstutorialspoint - Which field in the IP header is mutable and NOT protected by AH?
a. Source Address
b. TTL
c. Protocol
d. Version
Answer: b. TTLgeeksforgeeks+1 - What will be the status if an AH-authenticated packet is received out of order but within the window?
a. Processed and accepted
b. Dropped as replay
c. Flagged but processed
d. Queued indefinitely
Answer: a. Processed and acceptedgeeksforgeeks - AH is primarily used when which requirement is NOT needed?
a. Authentication
b. Integrity
c. Confidentiality
d. Anti-replay
Answer: c. Confidentialityscribd+1 - Which attacks are specifically mitigated by the sequence number in AH?
a. DOS attacks
b. Man-in-the-middle attacks
c. Replay attacks
d. Fragmentation attacks
Answer: c. Replay attacksnotes.networklessons+2 - Which protocol number is assigned to AH by IANA?
a. 50
b. 51
c. 53
d. 67
Answer: b. 51geeksforgeeks+1 - What does AH do when it detects unexpected changes in the authenticated portion of a packet?
a. Forwards the packet with warning
b. Discards the packet
c. Forwards the packet as is
d. Requests retransmission
Answer: b. Discards the packettutorialspoint - Which role does SPI in AH play in the context of Security Associations?
a. Identifies connection number
b. Identifies the Security Association to use
c. Indicates cryptographic algorithm only
d. No role
Answer: b. Identifies the Security Association to usesciencedirect+1 - How does AH perform in IPv6 compared to IPv4?
a. Only works in IPv4
b. Only supports multicast IPv6
c. Provides authentication and integrity for both
d. Encrypts IPv6 payloads
Answer: c. Provides authentication and integrity for bothlogsign+2 - What is the result if the authentication value does not match at the verifying end?
a. The packet is accepted
b. The packet is dropped
c. The packet is passed to the application for warning
d. The packet is re-sent for verification
Answer: b. The packet is droppedgeeksforgeeks+1 - When using transport mode, what is mainly protected by AH?
a. Entire original packet including inner headers
b. Payload and selected IP header fields
c. Outer IP header only
d. All IP headers and routing tables
Answer: b. Payload and selected IP header fieldsnotes.networklessons+2 - During IPsec operation, which protocol is typically paired with AH when confidentiality is also required?
a. AH again
b. TLS
c. ESP
d. PPTP
Answer: c. ESPnotes.networklessons+2 - Which field is incremented by the sender for every new packet sent in AH?
a. TTL
b. Sequence number
c. Version
d. Header length
Answer: b. Sequence numberexamtopics+1 - The use of mutable fields in the IP header, which are not protected by AH, is designed to:
a. Support NAT easily
b. Facilitate changes that occur during transit
c. Increase security
d. Compress packet size
Answer: b. Facilitate changes that occur during transittutorialspoint - Which situation most commonly leads to the choice of AH over ESP in a network?
a. Need for confidentiality
b. High performance routing
c. Need for only integrity and authentication
d. Requirement to support NAT
Answer: c. Need for only integrity and authenticationibm+2
- https://notes.networklessons.com/ipsec-authentication-header-ah
- https://www.ibm.com/support/pages/what-difference-between-ah-and-esp-protocols-ipsec
- https://www.cloudflare.com/en-in/learning/network-layer/what-is-ipsec/
- https://www.geeksforgeeks.org/computer-networks/internet-protocol-authentication-header/
- https://www.tutorialspoint.com/what-is-authentication-header-ah-format
- https://www.logsign.com/blog/authentication-header-in-network-security/
- https://www.sciencedirect.com/topics/computer-science/authentication-header
- https://www.reddit.com/r/networking/comments/2peaju/ipsec_why_use_authentication_header_ah_instead_of/
- https://www.examtopics.com/discussions/eccouncil/view/50170-exam-312-50v11-topic-1-question-62-discussion/
- https://www.scribd.com/doc/14484789/Multiple-Choice-Quiz-32
- https://www.ibm.com/docs/en/zos/3.1.0?topic=ipsec-ah-esp-protocols
- https://notes.networklessons.com/ipsec-esp-vs-ah
- https://www.sanfoundry.com/computer-networks-questions-answers-experienced/
- https://www.sanfoundry.com/computer-networks-questions-answers-ipsecurity/
- https://testbook.com/question-answer/ipsec-defines-two-protocols-_______-and-________–62b951f7356386339b3d67a4
- https://testbook.com/question-answer/which-of-the-following-statements-is-true–628f5cf45e47c9319f940001
- https://edurev.in/test/7067/Test-AH-ESP-Protocols
- https://erp.metbhujbalknowledgecity.ac.in/StudyMaterial/01VD062009003760041.pdf
- https://www.examtopics.com/discussions/fortinet/view/23100-exam-nse4_fgt-60-topic-1-question-120-discussion/
- https://www.gdcramban.in/MCQ/networkmcq.pdf