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Published 20 hours ago • verified publisher icon Revertron

Fix some errors in resolving

Open Revertron opened this issue 4 years ago • 2 comments

A report shows that ALFIS' resolver is not so consistent at times:

# dig ya.ru @318:1a0f:f6fd:77c::53

; <<>> DiG 9.11.5-P4-5.1-Debian <<>> ya.ru @318:1a0f:f6fd:77c::53
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 290
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 4

;; QUESTION SECTION:
;ya.ru.                         IN      A

;; ANSWER SECTION:
ya.ru.                  600     IN      A       87.250.250.242

;; AUTHORITY SECTION:
ya.ru.                  345600  IN      NS      ns2.yandex.ru.
ya.ru.                  345600  IN      NS      ns1.yandex.ru.

;; ADDITIONAL SECTION:
ns1.yandex.ru.          345600  IN      A       213.180.193.1
ns2.yandex.ru.          345600  IN      A       93.158.134.1
ns1.yandex.ru.          345600  IN      AAAA    2a02:6b8::1
ns2.yandex.ru.          345600  IN      AAAA    2a02:6b8:0:1::1

;; Query time: 301 msec
;; SERVER: 318:1a0f:f6fd:77c::53#53(318:1a0f:f6fd:77c::53)
;; WHEN: Wed Apr 14 18:35:20 UTC 2021
;; MSG SIZE  rcvd: 170

# dig ya.ru @318:1a0f:f6fd:77c::53

; <<>> DiG 9.11.5-P4-5.1-Debian <<>> ya.ru @318:1a0f:f6fd:77c::53
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 3749
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;ya.ru.                         IN      A

;; ANSWER SECTION:
ya.ru.                  600     IN      A       87.250.250.242

;; Query time: 0 msec
;; SERVER: 318:1a0f:f6fd:77c::53#53(318:1a0f:f6fd:77c::53)
;; WHEN: Wed Apr 14 18:35:26 UTC 2021
;; MSG SIZE  rcvd: 39

But there is another possible solution - change DNS code to some decent library instead of Hermes DNS server.

Revertron avatar Apr 14 '21 20:04 Revertron

I've checked it thoroughly, and it seems to me, that dig has some sort of cache. Subsequent requests by nslookup are showing consistent results.

Revertron avatar Apr 16 '21 17:04 Revertron

Can it be that reason is DNS cookies?

# dig ya.ru

; <<>> DiG 9.11.5-P4-5.1-Debian <<>> ya.ru
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 38901
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 5

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
; COOKIE: 463290231e49e8a03f1280c66079e58d9d0e7fe945bd9e64 (good)
;; QUESTION SECTION:
;ya.ru.                         IN      A

;; ANSWER SECTION:
ya.RU.                  600     IN      A       87.250.250.242

;; AUTHORITY SECTION:
ya.RU.                  345600  IN      NS      ns1.yandex.ru.
ya.RU.                  345600  IN      NS      ns2.yandex.ru.

;; ADDITIONAL SECTION:
ns1.yandex.RU.          345600  IN      A       213.180.193.1
ns2.yandex.RU.          345600  IN      A       93.158.134.1
ns1.yandex.RU.          345600  IN      AAAA    2a02:6b8::1
ns2.yandex.RU.          345600  IN      AAAA    2a02:6b8:0:1::1

;; Query time: 0 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)
;; WHEN: Fri Apr 16 19:29:17 UTC 2021
;; MSG SIZE  rcvd: 229

# dig ya.ru

; <<>> DiG 9.11.5-P4-5.1-Debian <<>> ya.ru
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 42698
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 5

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
; COOKIE: e66f4cf3c7363f302c21cda46079e592377074d046ffaccd (good)
;; QUESTION SECTION:
;ya.ru.                         IN      A

;; ANSWER SECTION:
ya.ru.                  600     IN      A       87.250.250.242

;; AUTHORITY SECTION:
YA.RU.                  345600  IN      NS      ns1.yandex.RU.
YA.RU.                  345600  IN      NS      ns2.yandex.RU.

;; ADDITIONAL SECTION:
ns1.yandex.RU.          345595  IN      A       213.180.193.1
ns2.yandex.RU.          345595  IN      A       93.158.134.1
ns1.yandex.RU.          345595  IN      AAAA    2a02:6b8::1
ns2.yandex.RU.          345595  IN      AAAA    2a02:6b8:0:1::1

;; Query time: 303 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)
;; WHEN: Fri Apr 16 19:29:22 UTC 2021
;; MSG SIZE  rcvd: 214

r4sas avatar Apr 16 '21 19:04 r4sas