The blackbox_exporter uses the built-in Go resolver library[0]. The only options here are which address family you want in return.
[0]: https://pkg.go.dev/net#Resolver.LookupIP On Thu, Aug 25, 2022 at 7:35 AM terrible person <[email protected]> wrote: > Thank you, actually I found out about this behaviour just after I posted > here. > Strangely, I don't see tcp connections with either nslookup of dig, though > response is about 860 bytes, but UDP outgoing traffic is present. When I > probe with blackbox there is also tcp. > > How blackbox performs such probes? In parallel or successively? Is there a > way to suspend such behaviour, analogue to +notcp option of dig? > > On Thursday, August 25, 2022 at 2:03:27 PM UTC+10 [email protected] wrote: > >> DNS lookups will switch to TCP if the response is larger than can fit in >> a single packet. But that should happen immediately. >> >> >> >> On Thu, Aug 25, 2022 at 5:56 AM terrible person <[email protected]> >> wrote: >> >>> Hi. I'm currently debugging DNS Lookup warnings (more that 3 sec) and >>> need to figure out whether our network/our DNS/or exporter is misbehaving. >>> So I'm checking ssh endpoints with tcp module: >>> >>> [image: 2022-08-25_13-22-13.png] >>> >>> but experience 3+ seconds delay on resolving ssh hostnames, which >>> triggers alerts DNSLookupDuration3s. >>> >>> [image: 2022-08-25_13-26-19.png] >>> problem looks something like this on different hosts - 3.0s+ seconds of >>> timeout, which looks very much like a generic tcp timeout. >>> >>> I checked on DNS server and yes, after UDP queries there is a TCP DNS >>> query for A record. I don't see any UDP checksum corruption or delays for >>> such failover. Is this intended? Can someone help me out on this. >>> >>> -- >>> You received this message because you are subscribed to the Google >>> Groups "Prometheus Users" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to [email protected]. >>> To view this discussion on the web visit >>> https://groups.google.com/d/msgid/prometheus-users/16d8f137-a7e3-4361-a624-6719d71b1d29n%40googlegroups.com >>> <https://groups.google.com/d/msgid/prometheus-users/16d8f137-a7e3-4361-a624-6719d71b1d29n%40googlegroups.com?utm_medium=email&utm_source=footer> >>> . >>> >> -- > You received this message because you are subscribed to the Google Groups > "Prometheus Users" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/prometheus-users/5f7bc297-5130-433b-b70c-6de34186a9e8n%40googlegroups.com > <https://groups.google.com/d/msgid/prometheus-users/5f7bc297-5130-433b-b70c-6de34186a9e8n%40googlegroups.com?utm_medium=email&utm_source=footer> > . > -- You received this message because you are subscribed to the Google Groups "Prometheus Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/prometheus-users/CABbyFmpb_TUR1MTzT%2Bni%3D6%3DVV9Lu2-37qfDmYSRxm8Z_13TqiA%40mail.gmail.com.
