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Whole document tree 7. A real domain exampleWhere we list some real zone files
Users have suggested that I include a real example of a working domain as well as the tutorial example.
I use this example with permission from David Bullock of LAND-5. These files were current 24th of September 1996, and were then edited to fit BIND 8 restrictions and use extensions by me. So, what you see here differs a bit from what you find if you query LAND-5's name servers now.
7.1 /etc/named.conf (or /var/named/named.conf)Here we find master zone sections for the two reverse zones needed:
the 127.0.0 net, as well as LAND-5's
// Boot file for LAND-5 name server options { directory "/var/named"; }; controls { inet 127.0.0.1 allow { localhost; } keys { rndc_key; }; }; key "rndc_key" { algorithm hmac-md5; secret "c3Ryb25nIGVub3VnaCBmb3IgYSBtYW4gYnV0IG1hZGUgZm9yIGEgd29tYW4K"; }; zone "." { type hint; file "root.hints"; }; zone "0.0.127.in-addr.arpa" { type master; file "zone/127.0.0"; }; zone "land-5.com" { type master; file "zone/land-5.com"; }; zone "177.6.206.in-addr.arpa" { type master; file "zone/206.6.177"; };
If you put this in your named.conf file to play with PLEASE
put ``
7.2 /var/named/root.hintsKeep in mind that this file is dynamic, and the one listed here is old. You're better off using a new one as explained earlier.
; <<>> DiG 8.1 <<>> @A.ROOT-SERVERS.NET. ; (1 server found) ;; res options: init recurs defnam dnsrch ;; got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 10 ;; flags: qr aa rd; QUERY: 1, ANSWER: 13, AUTHORITY: 0, ADDITIONAL: 13 ;; QUERY SECTION: ;; ., type = NS, class = IN ;; ANSWER SECTION: . 6D IN NS G.ROOT-SERVERS.NET. . 6D IN NS J.ROOT-SERVERS.NET. . 6D IN NS K.ROOT-SERVERS.NET. . 6D IN NS L.ROOT-SERVERS.NET. . 6D IN NS M.ROOT-SERVERS.NET. . 6D IN NS A.ROOT-SERVERS.NET. . 6D IN NS H.ROOT-SERVERS.NET. . 6D IN NS B.ROOT-SERVERS.NET. . 6D IN NS C.ROOT-SERVERS.NET. . 6D IN NS D.ROOT-SERVERS.NET. . 6D IN NS E.ROOT-SERVERS.NET. . 6D IN NS I.ROOT-SERVERS.NET. . 6D IN NS F.ROOT-SERVERS.NET. ;; ADDITIONAL SECTION: G.ROOT-SERVERS.NET. 5w6d16h IN A 192.112.36.4 J.ROOT-SERVERS.NET. 5w6d16h IN A 198.41.0.10 K.ROOT-SERVERS.NET. 5w6d16h IN A 193.0.14.129 L.ROOT-SERVERS.NET. 5w6d16h IN A 198.32.64.12 M.ROOT-SERVERS.NET. 5w6d16h IN A 202.12.27.33 A.ROOT-SERVERS.NET. 5w6d16h IN A 198.41.0.4 H.ROOT-SERVERS.NET. 5w6d16h IN A 128.63.2.53 B.ROOT-SERVERS.NET. 5w6d16h IN A 128.9.0.107 C.ROOT-SERVERS.NET. 5w6d16h IN A 192.33.4.12 D.ROOT-SERVERS.NET. 5w6d16h IN A 128.8.10.90 E.ROOT-SERVERS.NET. 5w6d16h IN A 192.203.230.10 I.ROOT-SERVERS.NET. 5w6d16h IN A 192.36.148.17 F.ROOT-SERVERS.NET. 5w6d16h IN A 192.5.5.241 ;; Total query time: 215 msec ;; FROM: roke.uio.no to SERVER: A.ROOT-SERVERS.NET. 198.41.0.4 ;; WHEN: Sun Feb 15 01:22:51 1998 ;; MSG SIZE sent: 17 rcvd: 436
7.3 /var/named/zone/127.0.0Just the basics, the obligatory SOA record, and a record that maps
127.0.0.1 to
$TTL 3D @ IN SOA land-5.com. root.land-5.com. ( 199609203 ; Serial 28800 ; Refresh 7200 ; Retry 604800 ; Expire 86400) ; Minimum TTL NS land-5.com. 1 PTR localhost.
If you look at a random BIND installation you will probably find
that the
7.4 /var/named/zone/land-5.comHere we see the mandatory SOA record, the needed NS records. We
can see that he has a secondary name server at
As you see from the SOA record, the zone file originates at
$TTL 3D @ IN SOA land-5.com. root.land-5.com. ( 199609206 ; serial, todays date + todays serial # 8H ; refresh, seconds 2H ; retry, seconds 4W ; expire, seconds 1D ) ; minimum, seconds NS land-5.com. NS ns2.psi.net. MX 10 land-5.com. ; Primary Mail Exchanger TXT "LAND-5 Corporation" localhost A 127.0.0.1 router A 206.6.177.1 land-5.com. A 206.6.177.2 ns A 206.6.177.3 www A 207.159.141.192 ftp CNAME land-5.com. mail CNAME land-5.com. news CNAME land-5.com. funn A 206.6.177.2 ; ; Workstations ; ws-177200 A 206.6.177.200 MX 10 land-5.com. ; Primary Mail Host ws-177201 A 206.6.177.201 MX 10 land-5.com. ; Primary Mail Host ws-177202 A 206.6.177.202 MX 10 land-5.com. ; Primary Mail Host ws-177203 A 206.6.177.203 MX 10 land-5.com. ; Primary Mail Host ws-177204 A 206.6.177.204 MX 10 land-5.com. ; Primary Mail Host ws-177205 A 206.6.177.205 MX 10 land-5.com. ; Primary Mail Host ; {Many repetitive definitions deleted - SNIP} ws-177250 A 206.6.177.250 MX 10 land-5.com. ; Primary Mail Host ws-177251 A 206.6.177.251 MX 10 land-5.com. ; Primary Mail Host ws-177252 A 206.6.177.252 MX 10 land-5.com. ; Primary Mail Host ws-177253 A 206.6.177.253 MX 10 land-5.com. ; Primary Mail Host ws-177254 A 206.6.177.254 MX 10 land-5.com. ; Primary Mail Host
If you examine land-5s nameserver you will find that the host names
are of the form
Another thing to note is that the workstations don't have individual names, but rather a prefix followed by the two last parts of the IP numbers. Using such a convention can simplify maintenance significantly, but can be a bit impersonal, and, in fact, be a source of irritation among your customers.
We also see that
7.5 /var/named/zone/206.6.177I'll comment on this file below
$TTL 3D @ IN SOA land-5.com. root.land-5.com. ( 199609206 ; Serial 28800 ; Refresh 7200 ; Retry 604800 ; Expire 86400) ; Minimum TTL NS land-5.com. NS ns2.psi.net. ; ; Servers ; 1 PTR router.land-5.com. 2 PTR land-5.com. 2 PTR funn.land-5.com. ; ; Workstations ; 200 PTR ws-177200.land-5.com. 201 PTR ws-177201.land-5.com. 202 PTR ws-177202.land-5.com. 203 PTR ws-177203.land-5.com. 204 PTR ws-177204.land-5.com. 205 PTR ws-177205.land-5.com. ; {Many repetitive definitions deleted - SNIP} 250 PTR ws-177250.land-5.com. 251 PTR ws-177251.land-5.com. 252 PTR ws-177252.land-5.com. 253 PTR ws-177253.land-5.com. 254 PTR ws-177254.land-5.com.
The reverse zone is the bit of the setup that seems to cause the
most grief. It is used to find the host name if you have the IP
number of a machine. Example: you are an FTP server and accept
connections from FTP clients. As you are a Norwegian FTP server you
want to accept more connections from clients in Norway and other
Scandinavian countries and less from the rest of the world. When you
get a connection from a client the C library is able to tell you the
IP number of the connecting machine because the IP number of the
client is contained in all the packets that are passed over the
network. Now you can call a function called gethostbyaddr that looks
up the name of a host given the IP number. Gethostbyaddr will ask a
DNS server, which will then traverse the DNS looking for the machine.
Supposing the client connection is from ws-177200.land-5.com. The IP
number the C library provides to the FTP server is 206.6.177.200. To
find out the name of that machine we need to find
The FTP server prioritizes connections from the Scandinavian
countries, i.e.,
Some people will tell you that reverse lookup mappings are only important for servers, or not important at all. Not so: Many ftp, news, IRC and even some http (WWW) servers will not accept connections from machines of which they are not able to find the name. So reverse mappings for machines are in fact mandatory.
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