101 · Question #110
When probing LDNSs, which protocol is used by default?
The correct answer is B. ICMP. BIG-IP GTM probes Local DNS servers (LDNSs) using ICMP by default to measure round-trip latency for proximity-based load balancing.
Question
When probing LDNSs, which protocol is used by default?
Options
- ATCP
- BICMP
- CDNS_REV
- DDNS_DOT
How the community answered
(22 responses)- B95% (21)
- C5% (1)
Why each option
BIG-IP GTM probes Local DNS servers (LDNSs) using ICMP by default to measure round-trip latency for proximity-based load balancing.
TCP is not the default LDNS probing protocol - TCP probing requires a full connection handshake and is used for virtual server health monitoring, not for default LDNS proximity probing.
ICMP is the default probing protocol for LDNSs in BIG-IP GTM because it provides a lightweight round-trip time measurement without requiring a full connection setup, and GTM uses these ICMP probe results to calculate proximity metrics for directing client traffic to the optimal resource.
DNS_REV is not a valid probing protocol option available in BIG-IP GTM for measuring LDNS latency.
DNS_DOT (DNS over TLS) is not a supported or default probing protocol used by BIG-IP GTM for LDNS proximity measurement.
Concept tested: BIG-IP GTM LDNS probing default protocol ICMP
Source: https://techdocs.f5.com/en-us/bigip-14-1-0/big-ip-dns-implementations/monitoring-big-ip-dns-server-resources.html
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