The first time you run this program, it will ask you for the address of a DNS. This will be your "home" or "default" server: "The one server you can always fall back on" and is often used by DNS Lookup's internal functions. You may enter either an IP address or a domain name, however IP numbers are prefered. If you enter a domain name (not an IP number) like "dns.fred.com", DNS Lookup will ask the MacTCP/Open Transport control panel to convert the name to an IP number (using the server supplied there.)
The main "Query Dialog"
This is the main dialog where you will probably be spending most of your time. You get to it by either typing "command-N" or selecting "New Lookup..." from the File Menu. There are lots of gadgets here... like:
• "Enter address/domain name:" question box
This (called the "question box") is where you type, copy or paste paste the IP numbers or domain names you wish to lookup (or in the case of AXFR, the zone you wish to transfer; see AXFR below.) IP Numbers must be of the format: X.X.X.X where each X is a number from zero and 255. Domain names are case-insensitive strings that contain only letters, numbers, hyphens "-", and uses dots "." to separate subdomains. Ex: "dns.freds-domain.com".
NOTE: Domain names entered must be fully qualified, e.g. no "joes.dns" instead of "joes.dns.fred.com".
• The "IP <-> Name" button
This useful little button converts IP numbers to domain names, and domain names to IP numbers. It converts back and forth whatever is in the question box to an IP number or domain name.
• "Query Method" popup menu
This alows you to choose which type of information you would like back. For example, if you know a domain name, but would like the IP number, you can use the "A (IP Address)" option in the menu. Keep in mind that not every server will support these query types; it is totally up to the people in charge of the domain you are doing the query on. Most query types prefer domain names rather than IP numbers, but PTR, for example, can take an IP number and "reverse map" it. Here are descriptions (which can be found in RFC's 1034 & 1035) of the varions query methods.
A - Returns the IP number or "internet address" of what was in the "question box", described above.
NS - Gives you an address of a server (another DNS) that is responsible for (or has authority over) the address in the question box.
CNAME - Some domain names are just nicknames, like www.fred.com could really be the machine
bigmac.fred.com. This returns the actual name or the "cannonical name."
SOA - Returns a buncha information about the domain (in the question box) that the server has authority over. The various response fields (from RFC 1035) are:
mname - the name of the server that was the primary source of data for this zone.
rname - the mailbox of the person responsible for this zone.
serial - the version number of the original copy of the zone.
refresh - time interval (in seconds) before the zone should be refreshed.
retry - time inverval (in seconds) that should elapse before a failed refresh
should be retried.
expire - time interval (in seconds) until that zone is no longer authorative.
minimum - time interval that should be exported with any RR.
MB - (experimental) Returns a host that has the mailbox in the question box.
MG - (experimental) Returns a mailbox which is a member of the mail group specified by the question box.
MR - (experimental) Returns a mailbox which is the proper rename of the mailbox in the question box.
WKS - Returns the IP address, as well as which services that address offers (i.e. telnet, ftp, smtp, http...)
PTR - Given an IP number, returns the corresponding domain name. (used to "reverse map" IP #'s)
HINFO - Returns the CPU type and operating system of the address in the question box.
MX - Gives the name of the machine (and preference number) that accepts mail (smtp usually) for the domain in the question box.
All - This returns as many records as possible pertaining to whatever was in the question box. Most servers seem to accept this type of query.
AXFR - "List all domains" or better known as "Zone Transfer", gives a complete list of all the sub domains of the domain in the question box. Example: to see all the machines fred is running in his domain, you would put in the question box: "fred.com", and that will list all domains that end with "fred.com", like "dns.fred.com". AXFR also accepts IP numbers, that is, typing "127.0.0" will display all IP numbers of the form "127.0.0.xx". Bear in mind that in both cases, the server needs to be an authority over these domains, otherwise it'll usually timeout on you. Note: This is usually a long list and very memory consuming, so you should "Capture it to a file" (see "Menus" below) to prevent information from being discarded becuse of memory constraints. If you run out of memory, try increasing the memory in the Finder's "Get Info" window.
</end of list>
If a server doesn't support one/any of thes query types, nothing is reported back (or, sometimes an error). For more information about the technicalities of these query types in general, read the DNS bible: RFC 1035 (found at Inter-Nic)
• the "Update Info" button
This will update the information that is directly below this button. This is especially useful when you have the "Reverse map IP #'s" option set in "Preferences..." and will refresh and reverse map the IP numbers shown.
• "Server Selection" radio buttons
These two buttons (to the left of the "update info" button) allow you to decide which server you acutaly wish to send the query to. Different servers will give you different responses. The "deafult" or "home" server is the one you can always fall back on. The "alternate" server is changeable by selecting the "New alternate server..." menu item; see "Menus" below. (Double-clicking the alternate server words, or address will also allow you to change the server address.)
• the "Close" and "Submit" buttons
Pressing the "Close" button closes the query dialog. The "Submit" button performs the actual query, and then displays the response recieved from the server chosen. Be sure you've checked over all the information in the dialog before submiting a query!
• ...and finaly: the Display Window
Here, you can see all the information that was recieved from the server. The information is displayed in the following format:
xxx yyy = zzz
where xxx is a domain name or IP address, zzz is information such as domain name, IP address, HINFO message, etc., and yyy explains the nature of what zzz is. NOTE: if xxx apears with parentheses: i.e. (xxx), then this indicates that this was contained in the "additional information" part of the response. This means that the DNS was being nice to you by supplying you with information you might want.
Menus
• File
"New Lookup..." - brings up a new query dialog, allowing you to send queries to servers.
"Close" - closes the query dialog
"Save Report..." - This saves whatever is in the "Display Window" of the query dialog to a text file. This is NOT the same as "Capture info to file" (see below)
"Quit" - exits the program.
• Edit
"Undo" - not implemented in this version.
"Cut/Copy/Paste/Clear/Select All" - those familiar funtions allowing you to maipulate text.
"Clear Report" - Resets the report in the "Display Window" and erases everything that was in it.
"Send info to screen" - when checked, will put everything recieved from the server into the "Display WIndow'
"Capture info to file" - when checked, will put everything recieved from the server directly into a file. This is not limited by the 32k text box limit imposed by the MacOS, and therfore is different from "Save Report..." (see above)
"Preferences" - Let's you change all the options of the program. For a description of these options, see "Preferences" below.
• Server
"New alternate server..." - allows you to select another server to query. You can either enter an IP number directly, or enter in a domain name. If you enter a domain name, you have a choice of deciding which server to convert this domain name to an IP number. If you choose the alternate server, it uses (of course) the alternate server chosen previously, and not the one you just entered. (?!)
Preferences
This dialog alows you to change the many features and options this program has to offer. In some sense, this gives you a lot of flexibility as to what kind of report is displayed. Here are descriptions of each option:
• Protocol
There are two (main) types of communication protocols on the internet today: TCP and UDP. Both are equaly as common but each has its pros & cons.
UDP - is the most common protocol for performing dns queries. It is connectionless, has a low overhead, and therefore more convenient for servers to recieve. It allows servers to reply on their own time, when they are ready. Because of this, it has also been deemed "less reliable." However, that is a relative term.
TCP - actualy makes a connection to the server (like a pipe) to exchange information. This requires more overhead, and most servers can accept finitely many connections, and therefore is not as convenient for the servers. It does provide for "more reliability" because packets cannot get "lost" the way they can with UDP. This is also the only acceptable protocol for zone transfers (see AXFR above.)
• Open Dialog at Startup
Brings up the query dialog immediately after running the program.
• Verbose comments
When displaying information the the "Display Window" (or the file, for that matter), clicking this option will provide extra diagnostic information about the information recieved and is useful in debuging and trcking down problems.
• Display all information recived
Sometimes the server responds with information that you didn't request. That's OK, but if you wish not to see a lot of it, do not select this option.
• Reverse map IP #'s
In the Query Dialog, there is some information displayed that indicates the IP numbers of the servers you are using. If you would like the program to also display the domain names of the servers click this option. With this option, every time you click "Update Info" it will reverse map the IP numbers using the server selected in the Query Dialog.
• Use Recursion
This is an option you can set to have the server use recursion if it is available. I'm not exactly sure what that entails, so if anyone knows, let me know and I'll put your words here!
• Use words for ports
Right now, this option only applies to "WKS" responses. Without this selected, a "WKS" response will look like:
With this option set, the text doesn't scroll by you as the information comes out, but the program just spits it out as fast as it can. If you are in a hurry, select this option.
• Sort output text
This option sorts the display alpabeticaly according to the first name written on the line. This is useful to get a better picture of what's going on, especially for zone transfers.
• DNS Timeout menu
This is how much time the program will wait for a response before giving up and returning a "Timeout" error
• Durring AXFR, Show:
This option lets you filter out which types of records you want durring a zone transfer. Selecting "A", for example will display only "inet address" type records. Selecting "Everything" will display everything recieved.
• Default Server IP:
This is the IP address of you "default" or "home" server. You can change this if you like, but you may only enter IP numbers. NO DOMAIN NAMES HERE, PLEASE!!!
That's everything I can think of documentation-wise.
-the end-
-Paul.
a540pau@pic.ucla.edu
P.S. Any example domains I gave are totally fictional. Any resemblance of these examples to actual domains is strictly coincedental. Sorry Fred.
