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rossburton's avatar
rossburton
Aspirant
May 29, 2021

Link-local used for IPv6 DNS server

Basically, https://community.netgear.com/t5/Orbi/Bug-RBR20-incorrectly-uses-link-local-router-IPv6-address-as/td-p/1887490   I turned on IPv6 and now my Orbi is telling DHCP clients that the DNS se...
rossburton's avatar
rossburton
Aspirant
May 30, 2021
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Aha. So the trick is that you need to specially handle v6 link-local addresses.  The address may be fe80::2a80:88ff:feeb:3cf8 but when it is used it needs to be qualified with the interface name:

 

$ dig @fe80::2a80:88ff:feeb:3cf8%en0 www.aa.net.uk
;; ANSWER SECTION:
www.aa.net.uk.		1287	IN	A	90.155.62.14
www.aa.net.uk.		1287	IN	A	90.155.62.13

And this qualification doesn't make it into /etc/resolv.conf so that's fun to deal with!

CrimpOn's avatar
CrimpOn
Guru - Experienced User
May 30, 2021
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I am still thrashing about.  Turns out dig for Windows is a lot easier for me to work with than (anything) on Linux.  (That business with DNS going through the loopback address and all.)

 

Here's what a dig query on  ibm.com looks like from my Orbi liink-local address:

c:\Bind>dig @fe80::a204:60ff:fe1c:239%19 ibm.com ANY

; <<>> DiG 9.16.16 <<>> @fe80::a204:60ff:fe1c:239%19 ibm.com ANY
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 39065
;; flags: qr rd ra; QUERY: 1, ANSWER: 31, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 512
;; QUESTION SECTION:
;ibm.com.                       IN      ANY

;; ANSWER SECTION:
ibm.com.                3599    IN      MX      5 mx0b-001b2d01.pphosted.com.
ibm.com.                3599    IN      MX      5 mx0a-001b2d01.pphosted.com.
ibm.com.                19      IN      A       96.17.216.124
ibm.com.                21599   IN      SOA     asia3.akam.net. dnsadm.us.ibm.com. 1564134900 43200 7200 604800 3600
ibm.com.                19      IN      AAAA    2600:1406:3400:6a1::3831
ibm.com.                19      IN      AAAA    2600:1406:3400:69d::3831
ibm.com.                599     IN      TXT     "amazonses:79ShwQazteb+WkCt8e297sAC2mwZVRditsrzaoxiHjU="
ibm.com.                599     IN      TXT     "00D3h000004YkeYEAS"
ibm.com.                599     IN      TXT     "00d50000000c9mweay"
ibm.com.                599     IN      TXT     "yandex-verification: 5f458b477256c50c"
ibm.com.                599     IN      TXT     "00d00000000hedieay"
ibm.com.                599     IN      TXT     "40a21f5affe343c6b37e0a5af80dcd93"
ibm.com.                599     IN      TXT     "Dynatrace-site-verification=76b6b299-fe43-4f31-889b-a8a467193478__8q74sg9dg5udjppn95utrb8bct"
ibm.com.                599     IN      TXT     "v=spf1 ip4:148.163.158.5 ip4:148.163.156.1 ip4:67.231.145.127 ip4:67.231.153.87 ip4:168.245.101.145 mx a:zgateway.zuora.com include:_spf.google.com ~all"
ibm.com.                599     IN      TXT     "atlassian-domain-verification=WAjTH82C5Zx475WLKAA2nrdlsoA/kN0ej9igrLrED4h15KMHPOm+A5H3GndKAxDC"
ibm.com.                599     IN      TXT     "google-site-verification=Jck8mLbYYfCnrmi_nRy4MG2fbUN3UGhC29KdspGLd9Y"
ibm.com.                599     IN      TXT     "adobe-idp-site-verification=5f8adca7-512f-44e1-a5b2-b62c5e3763f2"
ibm.com.                599     IN      TXT     "apple-domain-verification=M3o953J0rN1B0P2a"
ibm.com.                599     IN      TXT     "00df40000004784eaa"
ibm.com.                599     IN      TXT     "google-site-verification=tzdngH5fWH-k8uQoDVovOFJQZTwaGtDOP6S2cQlOvCs"
ibm.com.                599     IN      TXT     "_github-challenge-ibm.ibm.com=2613e984bc"
ibm.com.                599     IN      TXT     "facebook-domain-verification=kyuxs3tdqtyh9rbqa3szkq3k9i2bbs"
ibm.com.                599     IN      TXT     "MS=ms61389031"
ibm.com.                21599   IN      NS      usw2.akam.net.
ibm.com.                21599   IN      NS      asia3.akam.net.
ibm.com.                21599   IN      NS      eur2.akam.net.
ibm.com.                21599   IN      NS      usc3.akam.net.
ibm.com.                21599   IN      NS      ns1-206.akam.net.
ibm.com.                21599   IN      NS      eur5.akam.net.
ibm.com.                21599   IN      NS      ns1-99.akam.net.
ibm.com.                21599   IN      NS      usc2.akam.net.

;; Query time: 134 msec
;; SERVER: fe80::a204:60ff:fe1c:239%19#53(fe80::a204:60ff:fe1c:239%19)
;; WHEN: Sun May 30 15:21:59 Pacific Daylight Time 2021
;; MSG SIZE  rcvd: 1497

 

I am still of the opinion that Orbi giving out its IPv4 and IPv6 link local addresses as DNS servers "works".

I am also of the opinion that IPv6 is incredibly complicated and confusing and that a tremendous portion of the internet is not IPv6 friendly.

 

 

  • CrimpOn's avatar
    CrimpOn
    Guru - Experienced User
    May 30, 2021
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    An example of my confusion is the way web browsers totally manipulate the process.

    ford.com and honda.com do not have IPv6 addresses. (www.ford.com has IPv6 but www.honda.com does not).

     

    Open a web browser to http://ford.com (not https and not www.ford.com)  What does the browser produce?  https://www.ford.com

     

    And.... now that I find IPv6 addresses for URL's like www.ford.com, I have yet to get a browser to open the web site using IPv6.

     

    For me, networking continues to be a humbling experience.