[SR-Users] NAPTR/SRV lookups fail when use_dns_failover is enabled.

[Carsten Bock]

Hi,

we have the following settings and those work fine for us (Kamailio 4
and later):

# Do SRV-Loadbalancing:
dns_srv_lb=yes
# Always prefer IPv6:
dns_try_ipv6=yes
# DNS-Based failover
use_dns_failover=yes
# Query NAPTR-Records as well (we use NAPTR, so the client can detect
the outbound Proxy (P-CSCF), but internally we only use only
SRV-records)
dns_try_naptr=no

Sounds to me, like a DNS problem, not a Kamailio problem.

In our DNS Zone, we have the following, for example:

wt                      1D IN A         84.46.93.82
wt                      1D IN A         84.46.93.84
wt-1            1D IN A         84.46.93.82
wt-2            1D IN A         84.46.93.84
wt              1D IN NAPTR 10 10 "s" "SIP+D2U"         ""      _sip._udp.wt

_sip._udp.wt    1D SRV 10 1 5060 wt-1
_sip._udp.wt    1D SRV 20 1 5060 wt-2

On Debian/Ubuntu, you can verify this with Sofia-SIP (apt-get install
sofia-sip-bin):

carsten at carsten-HP-EliteBook-840-G3:~$ sip-dig wt.ng-voice.com
1 1.000 udp 5060 84.46.93.82
2 1.000 udp 5060 84.46.93.84

Thanks,
Carsten


2017-01-19 22:58 GMT+01:00 Jeremy Gadd <jeremygadd at gmail.com>:
> Hello, everyone!
>
> I'm trying to enable dns_srv_lb but I'm stuck just before I can get there.
> If I don't enable use_dns_failover, lookups work and calls route but always
> to the first host. We need to load balance, so that doesn't work very well.
>
> If I enable use_dns_failover, the lookups stop working completely and we get
> a dns lookup failure like so:
>  ERROR: tm [ut.h:296]: uri2dst2(): ERROR: uri2dst: failed to resolve
> "redacted.hostname.here.com" :unresolvable A or AAAA request (-7)
>
> This works:
> use_dns_cache=on
> dns_use_search_list=no
> dns_try_naptr=on
> # use_dns_failover=on
>
> This breaks it:
> use_dns_cache=on
> dns_use_search_list=no
> dns_try_naptr=on
> use_dns_failover=on
>
> I have checked to see that use_dns_failover is compiled in:
> version: kamailio 4.4.2 (x86_64/linux)
> flags: STATS: Off, USE_TCP, USE_TLS, USE_SCTP, TLS_HOOKS, USE_RAW_SOCKS,
> DISABLE_NAGLE, USE_MCAST, DNS_IP_HACK, SHM_MEM, SHM_MMAP, PKG_MALLOC,
> Q_MALLOC, F_MALLOC, TLSF_MALLOC, DBG_SR_MEMORY, USE_FUTEX,
> FAST_LOCK-ADAPTIVE_WAIT, USE_DNS_CACHE, USE_DNS_FAILOVER, USE_NAPTR,
> USE_DST_BLACKLIST, HAVE_RESOLV_RES
> ADAPTIVE_WAIT_LOOPS=1024, MAX_RECV_BUFFER_SIZE 262144, MAX_LISTEN 16,
> MAX_URI_SIZE 1024, BUF_SIZE 65535, DEFAULT PKG_SIZE 8MB
> poll method support: poll, epoll_lt, epoll_et, sigio_rt, select.
> id: unknown
> compiled with gcc 4.9.2
>
> _______________________________________________
> SIP Express Router (SER) and Kamailio (OpenSER) - sr-users mailing list
> sr-users at lists.sip-router.org
> http://lists.sip-router.org/cgi-bin/mailman/listinfo/sr-users
>



-- 
Carsten Bock
CEO (Geschäftsführer)

ng-voice GmbH
Millerntorplatz 1
20359 Hamburg / Germany

http://www.ng-voice.com
mailto:carsten at ng-voice.com

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