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    DNS lokup adding dmain name

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    • P
      PeterK2003
      last edited by

      Why when i do an nslookup on google.com is it returning with google.com.mydomain.com?

      Let me know what other info you need.

      Thanks,
      Peter

      1 Reply Last reply Reply Quote 0
      • johnpozJ
        johnpoz LAYER 8 Global Moderator
        last edited by

        that is a client setting to append search domains.

        could you post the output of your nslookup

        You normally would not see that unless you set debug, if you don't want it to happen you can end your host entry with .

        So for example here is query for google.com, notice return the answer – but if I set debug, see how it asked for both the A and AAAA records with my local.lan domain attached.

        
C:\>nslookup
Default Server:  pfsense.local.lan
Address:  192.168.1.253

> google.com
Server:  pfsense.local.lan
Address:  192.168.1.253

Non-authoritative answer:
Name:    google.com
Addresses:  74.125.225.82
          74.125.225.81
          74.125.225.84
          74.125.225.80
          74.125.225.83

> set debug
> google.com
Server:  pfsense.local.lan
Address:  192.168.1.253

------------
Got answer:
    HEADER:
        opcode = QUERY, id = 6, rcode = NXDOMAIN
        header flags:  response, want recursion, recursion avail.
        questions = 1,  answers = 0,  authority records = 1,  additional = 0

    QUESTIONS:
        google.com.local.lan, type = A, class = IN
    AUTHORITY RECORDS:
    ->  (root)
        ttl = 86261 (23 hours 57 mins 41 secs)
        primary name server = a.root-servers.net
        responsible mail addr = nstld.verisign-grs.com
        serial  = 2011110701
        refresh = 1800 (30 mins)
        retry   = 900 (15 mins)
        expire  = 604800 (7 days)
        default TTL = 86400 (1 day)

------------
------------
Got answer:
    HEADER:
        opcode = QUERY, id = 7, rcode = NXDOMAIN
        header flags:  response, want recursion, recursion avail.
        questions = 1,  answers = 0,  authority records = 1,  additional = 0

    QUESTIONS:
        google.com.local.lan, type = AAAA, class = IN
    AUTHORITY RECORDS:
    ->  (root)
        ttl = 86261 (23 hours 57 mins 41 secs)
        primary name server = a.root-servers.net
        responsible mail addr = nstld.verisign-grs.com
        serial  = 2011110701
        refresh = 1800 (30 mins)
        retry   = 900 (15 mins)
        expire  = 604800 (7 days)
        default TTL = 86400 (1 day)

------------
------------
Got answer:
    HEADER:
        opcode = QUERY, id = 8, rcode = NOERROR
        header flags:  response, want recursion, recursion avail.
        questions = 1,  answers = 5,  authority records = 0,  additional = 0

    QUESTIONS:
        google.com, type = A, class = IN
    ANSWERS:
    ->  google.com
        internet address = 74.125.225.82
        ttl = 161 (2 mins 41 secs)
    ->  google.com
        internet address = 74.125.225.81
        ttl = 161 (2 mins 41 secs)
    ->  google.com
        internet address = 74.125.225.84
        ttl = 161 (2 mins 41 secs)
    ->  google.com
        internet address = 74.125.225.80
        ttl = 161 (2 mins 41 secs)
    ->  google.com
        internet address = 74.125.225.83
        ttl = 161 (2 mins 41 secs)

------------
Non-authoritative answer:
------------
Got answer:
    HEADER:
        opcode = QUERY, id = 9, rcode = NOERROR
        header flags:  response, want recursion, recursion avail.
        questions = 1,  answers = 0,  authority records = 1,  additional = 0

    QUESTIONS:
        google.com, type = AAAA, class = IN
    AUTHORITY RECORDS:
    ->  google.com
        ttl = 474 (7 mins 54 secs)
        primary name server = ns1.google.com
        responsible mail addr = dns-admin.google.com
        serial  = 1467440
        refresh = 7200 (2 hours)
        retry   = 1800 (30 mins)
        expire  = 1209600 (14 days)
        default TTL = 300 (5 mins)

------------
Name:    google.com
Addresses:  74.125.225.82
          74.125.225.81
          74.125.225.84
          74.125.225.80
          74.125.225.83

>

        If use . on the end like google.com. then it doesn't do that

        
C:\>nslookup
Default Server:  pfsense.local.lan
Address:  192.168.1.253

> google.com.
Server:  pfsense.local.lan
Address:  192.168.1.253

Non-authoritative answer:
Name:    google.com
Addresses:  74.125.225.83
          74.125.225.84
          74.125.225.81
          74.125.225.82
          74.125.225.80

> set debug
> google.com.
Server:  pfsense.local.lan
Address:  192.168.1.253

------------
Got answer:
    HEADER:
        opcode = QUERY, id = 4, rcode = NOERROR
        header flags:  response, want recursion, recursion avail.
        questions = 1,  answers = 5,  authority records = 0,  additional = 0

    QUESTIONS:
        google.com, type = A, class = IN
    ANSWERS:
    ->  google.com
        internet address = 74.125.225.83
        ttl = 291 (4 mins 51 secs)
    ->  google.com
        internet address = 74.125.225.84
        ttl = 291 (4 mins 51 secs)
    ->  google.com
        internet address = 74.125.225.81
        ttl = 291 (4 mins 51 secs)
    ->  google.com
        internet address = 74.125.225.82
        ttl = 291 (4 mins 51 secs)
    ->  google.com
        internet address = 74.125.225.80
        ttl = 291 (4 mins 51 secs)

------------
Non-authoritative answer:
------------
Got answer:
    HEADER:
        opcode = QUERY, id = 5, rcode = NOERROR
        header flags:  response, want recursion, recursion avail.
        questions = 1,  answers = 0,  authority records = 1,  additional = 0

    QUESTIONS:
        google.com, type = AAAA, class = IN
    AUTHORITY RECORDS:
    ->  google.com
        ttl = 428 (7 mins 8 secs)
        primary name server = ns1.google.com
        responsible mail addr = dns-admin.google.com
        serial  = 1467441
        refresh = 7200 (2 hours)
        retry   = 1800 (30 mins)
        expire  = 1209600 (14 days)
        default TTL = 300 (5 mins)

------------
Name:    google.com
Addresses:  74.125.225.83
          74.125.225.84
          74.125.225.81
          74.125.225.82
          74.125.225.80

>

        Now you could turn off the use of search suffixes, but then would not allow you to do a dns query via just host name, like so

        
C:\>nslookup
Default Server:  pfsense.local.lan
Address:  192.168.1.253

> p4-28g
Server:  pfsense.local.lan
Address:  192.168.1.253

Name:    p4-28g.local.lan
Address:  192.168.1.4

> set debug
> p4-28g
Server:  pfsense.local.lan
Address:  192.168.1.253

------------
Got answer:
    HEADER:
        opcode = QUERY, id = 4, rcode = NOERROR
        header flags:  response, auth. answer, want recursion, recursion avail.
        questions = 1,  answers = 1,  authority records = 0,  additional = 0

    QUESTIONS:
        p4-28g.local.lan, type = A, class = IN
    ANSWERS:
    ->  p4-28g.local.lan
        internet address = 192.168.1.4
        ttl = 3600 (1 hour)

------------
------------
Got answer:
    HEADER:
        opcode = QUERY, id = 5, rcode = NOERROR
        header flags:  response, auth. answer, want recursion, recursion avail.
        questions = 1,  answers = 0,  authority records = 0,  additional = 0

    QUESTIONS:
        p4-28g.local.lan, type = AAAA, class = IN

------------
Name:    p4-28g.local.lan
Address:  192.168.1.4

        See how it auto added my local.lan to the search

        Now there is a group policy or reg key you can set to turn this control this functionality atleast for users of the dnsclient, like ping and browser, etc.  But nslookup is not effected – if you do not want nslookup to use your suffix and or search suffixes, etc. then just end the query with . like in my above example.

        Here is info on that reg key entry
        http://blogs.technet.com/b/networking/archive/2009/04/16/dns-client-name-resolution-behavior-in-windows-vista-vs-windows-xp.aspx
        DNS Client Name Resolution behavior in Windows Vista vs. Windows XP

        HKLM\Software\Policies\Microsoft\Windows NT\DNSClient\AppendToMultiLabelName

        Hope that helps!

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        If you get confused: Listen to the Music Play
        Please don't Chat/PM me for help, unless mod related
        SG-4860 24.11 | Lab VMs 2.7.2, 24.11

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        • jimpJ
          jimp Rebel Alliance Developer Netgate
          last edited by

          That happens most often when your domain has wildcard DNS active.

          The way DNS works, as laid out above, your search domain is appended before it queries farther up. Because you have wildcard DNS on, that returns a valid response.

          Without wildcard DNS, the entry does not exist, and it moves on to trying a higher level.

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