CS 742 - Domain Name System (DNS) I. nslookup 1. Execute the DNS client: $ nslookup 2. Query to obtain an IP-address: > www.cs.twsu.edu Server: 156.26.10.21 Address: 156.26.10.21#53 www.cs.twsu.edu canonical name = gladia.cs.twsu.edu. Name: gladia.cs.twsu.edu Address: 156.26.10.43 3. Set the server to be an authoritative twsu nameserver: > server wsuhub.uc.twsu.edu Default server: wsuhub.uc.twsu.edu Address: 156.26.1.1#53 4. Query using an authoritative server, and then a non-authoritative server: > www.cs.twsu.edu Server: wsuhub.uc.twsu.edu Address: 156.26.1.1#53 www.cs.twsu.edu canonical name = gladia.cs.twsu.edu. Name: gladia.cs.twsu.edu Address: 156.26.10.43 > www.yahoo.com Server: wsuhub.uc.twsu.edu Address: 156.26.1.1#53 Non-authoritative answer: www.yahoo.com canonical name = www.yahoo.akadns.net. Name: www.yahoo.akadns.net Address: 64.58.76.222 Name: www.yahoo.akadns.net Address: 64.58.76.229 Name: www.yahoo.akadns.net Address: 64.58.76.228 Name: www.yahoo.akadns.net Address: 64.58.76.178 Name: www.yahoo.akadns.net Address: 64.58.76.176 Name: www.yahoo.akadns.net Address: 64.58.76.177 Name: www.yahoo.akadns.net Address: 64.58.76.179 Name: www.yahoo.akadns.net Address: 64.58.76.227 Name: www.yahoo.akadns.net Address: 64.58.76.224 Name: www.yahoo.akadns.net Address: 64.58.76.230 Name: www.yahoo.akadns.net Address: 64.58.76.223 Name: www.yahoo.akadns.net Address: 64.58.76.225 5. Request host information: > set type=HINFO > depot.cis.ksu.edu Server: wsuhub.uc.twsu.edu Address: 156.26.1.1#53 Non-authoritative answer: depot.cis.ksu.edu canonical name = ntp.ksu.edu. Authoritative answers can be found from: ksu.edu origin = ns-1.ksu.edu mail addr = dns.ksu.edu serial = 2002120300 refresh = 7200 retry = 1200 expire = 2592000 minimum = 7200 6. Query to obtain a canonical name: > set type=CNAME > www.yahoo.com Server: wsuhub.uc.twsu.edu Address: 156.26.1.1#53 Non-authoritative answer: www.yahoo.com canonical name = www.yahoo.akadns.net. Authoritative answers can be found from: yahoo.COM nameserver = NS1.yahoo.COM. yahoo.COM nameserver = NS2.yahoo.COM. yahoo.COM nameserver = NS3.yahoo.COM. yahoo.COM nameserver = NS4.yahoo.COM. yahoo.COM nameserver = NS5.yahoo.COM. NS1.yahoo.COM internet address = 66.218.71.63 NS2.yahoo.COM internet address = 209.132.1.28 NS3.yahoo.COM internet address = 217.12.4.104 NS4.yahoo.COM internet address = 63.250.206.138 NS5.yahoo.COM internet address = 64.58.77.85 7. Query mail exchange records: > set type=MX > cis.ksu.edu Server: wsuhub.uc.twsu.edu Address: 156.26.1.1#53 Non-authoritative answer: cis.ksu.edu mail exchanger = 20 zaurak.cis.ksu.edu. cis.ksu.edu mail exchanger = 10 rigel.cis.ksu.edu. Authoritative answers can be found from: cis.ksu.edu nameserver = ns-2.cis.ksu.edu. cis.ksu.edu nameserver = ns-1.cis.ksu.edu. cis.ksu.edu nameserver = ns-1.ksu.edu. cis.ksu.edu nameserver = ns-2.ksu2edu. zaurak.cis.ksu.edu internet address = 129.130.10.3 rigel.cis.ksu.edu internet address = 129.130.10.65 ns-2.cis.ksu.edu internet address = 129.130.10.65 ns-1.cis.ksu.edu internet address = 129.130.10.3 ns-1.ksu.edu internet address = 129.130.12.21 8. Get a list of commands: > ? Commands: (identifiers are shown in uppercase, [] means optional) NAME - print info about the host/domain NAME using default server NAME1 NAME2 - as above, but use NAME2 as server help or ? - print help information set OPTION - set an option all - print options, current server and host [no]debug - print debugging information [no]d2 - print exhaustive debugging information [no]defname- append domain name to each query [no]recurse- ask for recursive answer to query [no]vc - always use a virtual circuit domain=NAME- set default domain name to NAME root=NAME - set root server to NAME retry=X - set number of retries to X timeout=X - set time-out interval to X querytype=X- set query type to one of A,CNAME,HINFO,MB,MG,MINFO,MR,MX, NS,SOA,WKS,PTR,AXFR,MAILB,ANY,UINFO,UID,GID type=X - set query type to one of A,CNAME,HINFO,MB,MG,MINFO,MR,MX NS,SOA,WKS,PTR,AXFR,MAILB,ANY,UINFO,UID,GID server NAME - set default server to NAME, using current default server lserver NAME- set default server to NAME, using initial server finger [NAME]- finger the optional NAME root - set current default server to the root ls NAME [> FILE]- list the domain NAME, with output optionally going to FILE view FILE - sort an 'ls' output file and view it with more II. dig $ dig www.yahoo.com dig www.yahoo.com ;; Truncated, retrying in TCP mode. ; <<>> DiG 9.2.1 <<>> www.yahoo.com ;; global options: printcmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 13139 ;; flags: qr rd ra; QUERY: 1, ANSWER: 9, AUTHORITY: 11, ADDITIONAL: 11 ;; QUESTION SECTION: ;www.yahoo.com. IN A ;; ANSWER SECTION: www.yahoo.com. 300 IN CNAME www.yahoo.akadns.net. www.yahoo.akadns.net. 60 IN A 68.142.226.33 www.yahoo.akadns.net. 60 IN A 68.142.226.37 www.yahoo.akadns.net. 60 IN A 68.142.226.56 www.yahoo.akadns.net. 60 IN A 68.142.226.44 www.yahoo.akadns.net. 60 IN A 68.142.226.35 www.yahoo.akadns.net. 60 IN A 68.142.226.51 www.yahoo.akadns.net. 60 IN A 68.142.226.46 www.yahoo.akadns.net. 60 IN A 68.142.226.39 ;; AUTHORITY SECTION: akadns.net. 4626 IN NS asia3.akadns.net. akadns.net. 4626 IN NS eur3.akadns.net. akadns.net. 4626 IN NS use2.akadns.net. akadns.net. 4626 IN NS use4.akadns.net. akadns.net. 4626 IN NS usw5.akadns.net. akadns.net. 4626 IN NS usw6.akadns.net. akadns.net. 4626 IN NS usw7.akadns.net. akadns.net. 4626 IN NS za.akadns.org. akadns.net. 4626 IN NS zc.akadns.org. akadns.net. 4626 IN NS zf.akadns.org. akadns.net. 4626 IN NS zh.akadns.org. ;; ADDITIONAL SECTION: asia3.akadns.net. 166874 IN A 65.203.234.27 eur3.akadns.net. 166874 IN A 193.45.1.103 use2.akadns.net. 166874 IN A 63.209.170.136 use4.akadns.net. 166874 IN A 80.67.67.182 usw5.akadns.net. 166874 IN A 63.241.73.214 usw6.akadns.net. 166874 IN A 206.132.100.108 usw7.akadns.net. 166874 IN A 65.203.234.27 za.akadns.org. 13274 IN A 208.185.132.176 zc.akadns.org. 13274 IN A 63.241.199.54 zf.akadns.org. 13274 IN A 63.241.29.161 zh.akadns.org. 13274 IN A 63.208.48.46 ;; Query time: 5 msec ;; SERVER: 156.26.10.2#53(156.26.10.2) ;; WHEN: Sun Nov 28 12:40:56 2004 ;; MSG SIZE rcvd: 581