300-730 · Question #1
Which VPN solution uses TBAR?
The correct answer is A. GETVPN. GET VPN uses Time-Based Anti-Replay (TBAR) instead of sequence-number-based anti-replay because it preserves the original IP header and operates in a tunnel-less architecture.
Question
Options
- AGETVPN
- BVTI
- CDMVPN
- DCisco AnyConnect
How the community answered
(27 responses)- A93% (25)
- B4% (1)
- D4% (1)
Why each option
GET VPN uses Time-Based Anti-Replay (TBAR) instead of sequence-number-based anti-replay because it preserves the original IP header and operates in a tunnel-less architecture.
GET VPN (Group Encrypted Transport VPN) uses TBAR because it does not encapsulate packets in a new IP header, so traditional counter-based anti-replay mechanisms are not viable. TBAR relies on synchronized clocks across key servers and group members to detect replayed packets within a configurable time window. This is a defining architectural feature that distinguishes GET VPN from other VPN technologies.
VTI (Virtual Tunnel Interface) uses standard IPsec with sequence-number-based anti-replay, not TBAR.
DMVPN uses IPsec for encryption with standard sequence-based anti-replay, and does not employ TBAR.
Cisco AnyConnect uses SSL/TLS or DTLS for transport and does not use TBAR as an anti-replay mechanism.
Concept tested: GET VPN Time-Based Anti-Replay (TBAR)
Source: https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/sec_conn_getvpn/configuration/xe-3s/sec-get-vpn-xe-3s-book/sec-get-vpn.html
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