DNS troubleshooting

The following diagnose command can be used to collect DNS debug information. If you do not specify worker ID, the default worker ID is 0.

# diagnose test application dnsproxy 
worker idx: 0
1. Clear DNS cache
2. Show stats
3. Dump DNS setting
4. Reload FQDN
5. Requery FQDN
6. Dump FQDN
7. Dump DNS cache
8. Dump DNS DB
9. Reload DNS DB
10. Dump secure DNS policy/profile
11. Dump Botnet domain
12. Reload Secure DNS setting
13. Show Hostname cache
14. Clear Hostname cache
15. Show SDNS rating cache
16. Clear SDNS rating cache
17. DNS debug bit mask
99. Restart dnsproxy worker

To view useful information about the ongoing DNS connection:

# diagnose test application dnsproxy 3
worker idx: 0
vdom: root, index=0, is master, vdom dns is disabled, mip-169.254.0.1 dns_log=1 tls=0 cert=
dns64 is disabled
vdom: vdom1, index=1, is master, vdom dns is enabled, mip-169.254.0.1 dns_log=1 tls=0 cert=
dns64 is disabled
dns-server:208.91.112.220:53 tz=-480 tls=0 req=0 to=0 res=0 rt=0 rating=1 ready=0 timer=37 probe=9 failure=0 last_failed=0 
dns-server:8.8.8.8:53 tz=0 tls=0 req=73 to=0 res=73 rt=5 rating=0 ready=1 timer=0 probe=0 failure=0 last_failed=0 
dns-server:65.39.139.63:53 tz=0 tls=0 req=39 to=0 res=39 rt=1 rating=0 ready=1 timer=0 probe=0 failure=0 last_failed=0 
dns-server:62.209.40.75:53 tz=60 tls=0 req=0 to=0 res=0 rt=0 rating=1 ready=0 timer=37 probe=9 failure=0 last_failed=0 
dns-server:209.222.147.38:53 tz=-300 tls=0 req=0 to=0 res=0 rt=0 rating=1 ready=0 timer=37 probe=9 failure=0 last_failed=0 
dns-server:173.243.138.221:53 tz=-480 tls=0 req=0 to=0 res=0 rt=0 rating=1 ready=0 timer=37 probe=9 failure=0 last_failed=0 
dns-server:45.75.200.89:53 tz=0 tls=0 req=0 to=0 res=0 rt=0 rating=1 ready=0 timer=37 probe=9 failure=0 last_failed=0 
DNS_CACHE: hash-size=2048, ttl=1800, min-ttl=60, max-num=-1
DNS FD: udp_s=12 udp_c=17:18 ha_c=22 unix_s=23, unix_nb_s=24, unix_nc_s=25 
        v6_udp_s=11, v6_udp_c=20:21, snmp=26, redir=13, v6_redir=14
DNS FD: tcp_s=29, tcp_s6=27, redir=31 v6_redir=32
FQDN: hash_size=1024, current_query=1024
DNS_DB: response_buf_sz=131072
LICENSE: expiry=2015-04-08, expired=1, type=2
FDG_SERVER:208.91.112.220:53 
FGD_CATEGORY_VERSION:8
SERVER_LDB: gid=eb19, tz=-480, error_allow=0
FGD_REDIR_V4:208.91.112.55 FGD_REDIR_V6:

Important fields include:

tls	1 if the connection is TLS, 0 if the connection is not TLS.
rt	The round trip time of the DNS latency.
probe	The number of probes sent.

To dump the second DNS worker's cache:

diagnose test application dnsproxy 7 1

To enable debug on the second worker:

diagnose debug application dnsproxy -1 1

To enable debug on all workers by specifying -1 as worker ID:

diagnose debug application dnsproxy -1 -1