16 ; (My web server) serial 86400 ; refresh: once per
16 ; serial 86400 ; refresh: once per day 3600 ; retry: one hour 3600000 ; expire: 42 days 604800 ; minimum: 1 week ) IN NS vlager.vbrew.com. ; brewery 1.1 IN PTR vlager.vbrew.com. 2.1 IN PTR vstout.vbrew.com. 3.1 IN PTR vale.vbrew.com. ; winery 1.2 IN PTR vlager-if2.vbrew.com. 2.2 IN PTR vbardolino.vbrew.com. 3.2 IN PTR vchianti.vbrew.com. 4.2 IN PTR vbeaujolais.vbrew.com. Verifying the Name Server Setup nslookup is a great tool for checking the operation of your name server setup. It can be used both interactively with prompts and as a single command with immediate output. In the latter case, you simply invoke it as: $ nslookup hostname nslookup queries the name server specified in resolv.conf for hostname. (If this file names more than one server, nslookup chooses one at random.) The interactive mode, however, is much more exciting. Besides looking up individual hosts, you may query for any type of DNS record and transfer the entire zone information for a domain. When invoked without an argument, nslookup displays the name server it uses and enters interactive mode. At the > prompt, you may type any domain name you want to query. By default, it asks for class A records, those containing the IP address relating to the domain name. You can look for record types by issuing: > set type=type in which type is one of the resource record names described earlier, or ANY. You might have the following nslookup session: $ nslookup Default Server: tao.linux.org.au Address: 203.41.101.121 > metalab.unc.edu Server: tao.linux.org.au Address: 203.41.101.121 Name: metalab.unc.edu Address: 152.2.254.81 The output first displays the DNS server being queried, and then the result of the query. If you try to query for a name that has no IP address associated with it, but other records were found in the DNS database, nslookup returns with an error message saying “No type A records found.” However, you can make it query for records other than type A by issuing the set type command. To get the SOA record of unc.edu, you would issue: > unc.edu Server: tao.linux.org.au Address: 203.41.101.121