Cheatsheet & Examples: nslookup

Looking up Hostname

Example Usage: nslookup example.com

What it does: This operation retrieves the IP address associated with a given hostname.

Command-line Arguments Explained:

• example.com: The hostname to be looked up. This can be a domain name or a subdomain.

Querying for IP Address

Example Usage: nslookup 8.8.8.8

What it does: This operation retrieves the hostname associated with a given IP address.

Command-line Arguments Explained:

• 8.8.8.8: The IP address to be looked up.

Setting Query Type

Example Usage: nslookup -type=mx example.com

What it does: This operation retrieves the mail exchange (MX) records associated with a given hostname.

Command-line Arguments Explained:

• -type=mx: Specifies the query type. Common types include A (IP address), MX (mail exchange), NS (name server), and SOA (start of authority).
• example.com: The hostname to be looked up.

Using a Specific DNS Server

Example Usage: nslookup -server=8.8.8.8 example.com

What it does: This operation retrieves the IP address associated with a given hostname using a specified DNS server.

Command-line Arguments Explained:

• -server=8.8.8.8: Specifies the DNS server to use for the lookup. This can be an IP address or a hostname.
• example.com: The hostname to be looked up.

Looking up a SoA Record

Example Usage: nslookup -type=soa example.com

What it does: This operation retrieves the start of authority (SOA) record associated with a given hostname.

Command-line Arguments Explained:

• -type=soa: Specifies the query type as SOA (start of authority).
• example.com: The hostname to be looked up.

Using a Non-Routing DNS Server

Example Usage: nslookup -ns=8.8.8.8 example.com

What it does: This operation retrieves the IP address associated with a given hostname using a non-routing DNS server.

Command-line Arguments Explained:

• -ns=8.8.8.8: Specifies the non-routing DNS server to use for the lookup. This can be an IP address or a hostname.
• example.com: The hostname to be looked up.

Setting the Port Number

Example Usage: nslookup -port=53 example.com

What it does: This operation retrieves the IP address associated with a given hostname using a specified port number.

Command-line Arguments Explained:

• -port=53: Specifies the port number to use for the DNS query. The default port number is 53.
• example.com: The hostname to be looked up.

Looking up a PTR Record

Example Usage: nslookup -type=ptr 8.8.8.8

What it does: This operation retrieves the pointer (PTR) record associated with a given IP address.

Command-line Arguments Explained:

• -type=ptr: Specifies the query type as PTR (pointer).
• 8.8.8.8: The IP address to be looked up.

Using the +options Flag

Example Usage: nslookup +options example.com

What it does: This operation retrieves the IP address associated with a given hostname with additional options.

Command-line Arguments Explained:

• +options: Enables additional options for the nslookup command. The specific options depend on the version of nslookup being used.
• example.com: The hostname to be looked up.