Testing the DNS Name Resolution: Difference between revisions
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On Windows and *nix, you can use „nslookup“ to test if your computer can resolve records by using your DNS. Try resolving the name of your Domain Controller into its IP: |
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= Introduction = |
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</noinclude> |
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To verify that your DNS settings are correct and your client or server is able to resolve IP addresses and host names use the <code>nslookup</code> command. The command is available on Linux and Windows. |
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== Forward Lookup == |
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To resolve a host name its IP address: |
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# nslookup DC1.samdom.example.com |
# nslookup DC1.samdom.example.com |
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Server: |
Server: 10.99.0.1 |
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Address: |
Address: 10.99.0.1#53 |
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Name: DC1.samdom.example.com |
Name: DC1.samdom.example.com |
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Address: |
Address: 10.99.0.1 |
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Nslookup will show you, which server was asked (192.168.1.1) and the result of your query (DC1.samdom.example.com has IP 192.168.1.1) |
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To query a SVR record, you have to start nslookup and set the type to „SRV“, to retrieve the values (works on Windows and *nix): |
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Default Server: UnKnown |
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== Reverse Lookup == |
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To resolve a IP address to its host name: |
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# nslookup 10.99.0.1 |
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Server: 10.99.0.1 |
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Note that in a Samba AD, the reverse zone is not automatically configured. To set up a reverse zone, see [[DNS_Administration|DNS Administration]]. |
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== Resolving SRV Records == |
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Active Directory (AD) uses SRV records to locate services, such as Kerberos and LDAP. To verify that SRV records are resolved correctly, use the <code>nslookup</code> interactive shell: |
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> set type=SRV |
> set type=SRV |
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> _ldap._tcp.samdom.example.com |
> _ldap._tcp.samdom.example.com |
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Server: |
Server: 192.168.0.4 |
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Address: |
Address: 192.168.0.4#53 |
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_ldap._tcp.samdom.example.com |
_ldap._tcp.samdom.example.com service = 0 100 389 dc2.samdom.example.com. |
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priority = 0 |
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> exit |
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weight = 100 |
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port = 389 |
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dc1.samdom.example.com internet address = 192.168.1.1 |
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Alternatively, you can use the host command. |
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If your query can't be answered, because it doesn't exist, you'll receive |
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$ host -t SRV _ldap._tcp.samdom.example.com |
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_ldap._tcp.samdom.example.com has SRV record 0 100 389 dc1.samdom.example.com. |
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_ldap._tcp.samdom.example.com has SRV record 0 100 389 dc2.samdom.example.com. |
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== Error Messages == |
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* The DNS server is not able to resolve the host name: |
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** server can't find DC1.samdom.example.com: NXDOMAIN |
** server can't find DC1.samdom.example.com: NXDOMAIN |
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* The DNS server is not able to resolve the IP address: |
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If you query a none existing DNS server, it would result in |
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** server can't find 1.0.99.10.in-addr.arpa: NXDOMAIN |
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* The DNS server used is not available: |
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;; connection timed out; no servers could be reached |
;; connection timed out; no servers could be reached |
Revision as of 07:51, 9 October 2021
Introduction
To verify that your DNS settings are correct and your client or server is able to resolve IP addresses and host names use the nslookup
command. The command is available on Linux and Windows.
Forward Lookup
To resolve a host name its IP address:
# nslookup DC1.samdom.example.com Server: 10.99.0.1 Address: 10.99.0.1#53 Name: DC1.samdom.example.com Address: 10.99.0.1
Reverse Lookup
To resolve a IP address to its host name:
# nslookup 10.99.0.1 Server: 10.99.0.1 Address: 10.99.0.1#53 1.0.99.10.in-addr.arpa name = DC1.samdom.example.com.
Note that in a Samba AD, the reverse zone is not automatically configured. To set up a reverse zone, see DNS Administration.
Resolving SRV Records
Active Directory (AD) uses SRV records to locate services, such as Kerberos and LDAP. To verify that SRV records are resolved correctly, use the nslookup
interactive shell:
$ nslookup > set type=SRV > _ldap._tcp.samdom.example.com Server: 192.168.0.4 Address: 192.168.0.4#53 _ldap._tcp.samdom.example.com service = 0 100 389 dc2.samdom.example.com. _ldap._tcp.samdom.example.com service = 0 100 389 dc1.samdom.example.com. > exit
Alternatively, you can use the host command.
$ host -t SRV _ldap._tcp.samdom.example.com _ldap._tcp.samdom.example.com has SRV record 0 100 389 dc1.samdom.example.com. _ldap._tcp.samdom.example.com has SRV record 0 100 389 dc2.samdom.example.com.
Error Messages
- The DNS server is not able to resolve the host name:
** server can't find DC1.samdom.example.com: NXDOMAIN
- The DNS server is not able to resolve the IP address:
** server can't find 1.0.99.10.in-addr.arpa: NXDOMAIN
- The DNS server used is not available:
;; connection timed out; no servers could be reached