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DNS

Most web sites require an entry in the Domain Name System (DNS) in order to be useful. DNS provides translation of Internet Protocol (IP) addresses into names and vice versa. A DNS name is a meaningful and easy-to-remember "handle" for an IP address.

DNS names usually contain two parts: a hostname and a domain name. In the name www.jhu.edu, www is the hostname and jhu.edu is the domain name. Together the hostname and domain name are referred to as a Fully Qualified Domain Name (FQDN).

To request or modify a name in the Hopkins DNS system, use the DNS Request and Maintenance Utility (http://jhedi.hosts.jhmi.edu/dns/). It is necessary to have a static IP address for the site or server in order to resolve the friendly name which is registered in DNS. You may need to obtain your static IP address before filling out the DNS application. If you need an IP address for a computer located on the Homewood campus, use this form: http://nts.jhu.edu/networking/iprequest.cfm . For IP addresses in East Baltimore and other locations you must contact your LAN Administrator. If the web site will be reachable from outside the campuses, the static IP address cannot be in the private address space (http://www.isi.edu/in-notes/rfc1918.txt).

Specific notes for different types of DNS names:

Hopkins Root Level Names

Root level domain names require justification and are not given out to normal hosts. Servers that are used by the entire Hopkins community, and not just a specific group, are good candidates for root level names. In addition to the regular form, you will be asked to complete a special form for root level domain requests. You may be contacted during the review of your special request for additional justification or information.

Hopkins Subdomain Names

In this example, the root level domains bio.jhu.edu and labs.jhmi.edu have already been established in the Hopkins DNS. These domains may be managed by the department or by Enterprise Services. In these cases, you may have to contact the department that manages the root level domain instead of going through Enterprise Services.

Non-Hopkins Domain Names (non jhu.edu/jhmi.edu)

This type of name must be purchased and registered using an outside registrar. To find a list of ICANN-approved registrars, look here http://www.internic.net/regist.html. If the server is going to reside on the Hopkins network, then it is recommended that Hopkins handle the DNS for the server. Permission for Hopkins to resolve a non jhu.edu or jhmi.edu address should be obtained before the name is purchased. Use the DNS Request and Maintenance Utility to obtain permission. Once permission is obtained from Hopkins, use the following settings when purchasing the name from the registrar:

Technical Contact: ISA9-ORG

Nameservers: ens1.jhmi.edu, ens1.jhu.edu

The registrar may have to contact Hopkins before the entries are finalized. It must be stressed that simply using these settings without first obtaining permission will not work. The name has to be added to Hopkins' DNS before the above settings will work. And before the name can be added to Hopkins' DNS, permission must be obtained.

As a general rule, .com addresses are not allowed in the Hopkins DNS systems. To preserve our .edu status, it is important that Johns Hopkins not use our DNS for commercial enterprises. Most requests for Non-Hopkins Domain Names are for .org addresses. If the entity making the request is a part of Hopkins and the web site is not going to be used for commercial purposes, most .org requests are approved. There may be technical or organizational reasons for denying a .org request, so it is important to get approval before making a purchase. On the other hand, most requests for .com names and any request related to a commercial enterprise are usually denied. If the name being registered is a high profile name and there are concerns about misappropriation by an outside party, it is possible to have Hopkins host the .org address and purchase the .com, .net, .biz, .info, etc. domains but not have them resolve anywhere. Buying all possible top-level domain names for a given site is an increasingly expensive and maintenance intensive strategy, so it should be considered carefully.

Having the name entered in Hopkins DNS does not mean that email will work using that domain name. This service is not provided by Hopkins. For instance, if Hopkins DNS were being used to resolve www.hopkinsbio.org, you could not use user@hopkinsbio.org as an email address and expect it to automatically work.

It is possible to use an outside company's DNS to resolve a name back to a server on the Hopkins network. This method is not supported by Hopkins and no guarantees can be made for the reliability of an outside company's DNS servers. Many companies also offer a service called URL Forwarding. Typically in URL Forwarding, the outside registrar resolves the name using their DNS, but then forwards the browser on to another address. So, a user may type in www.hopkinsbio.org and be automatically forwarded to www.bio.jhu.edu . This service offers some degree of flexibility since the forwarding address can usually be changed easily, but also has some drawbacks because the URL of the site is not persistent throughout the user's visit.

If the site resides outside the Hopkins network, then arrangement must be made with the party hosting the site to provide DNS resolution. Hopkins' DNS only resolves names that point back to IP addresses on the Hopkins network.

Whether the server resides on the Hopkins network or not, it is up to the party requesting the name to pay all fees and perform all maintenance on the external name.

One web server is often configured to answer many different names. This can be accomplished using several different methods, depending on the operating system and web server software. In most cases, one of two methods is used:

1. Binding multiple IP addresses to one server. In this method the network interfaces in the server are assigned more than one IP address. When requesting multiple DNS names, each unique name would be assigned to one of the different IP addresses bound to the server. This method is rarely used at Hopkins because servers are usually only allotted one IP address.
2. Virtual Hosts (apache) and Host Headers (IIS). These methods allow the web server to answer many different DNS names while using only one IP Address. When requesting DNS names and using these methods, each DNS request would point back to the same IP address. The web server software is then configured to examine the HTTP header request and route the request to the appropriately named site on the server. It is important to understand that this method requires configuration changes in both DNS and the web server. For example, both of the names nts.jhu.edu and nts.jhmi.edu point to the same web site. When this web site was setup, each name received its own entry in DNS, but both names resolve back to the same IP address.

Special note on new .edu domains:

The contact email for questions about DNS is either hostmaster@jhmi.edu (jhmi.edu names) or hostmaster@jhu.edu (jhu.edu names).

More information on Hopkins' DNS can currently be found here: http://nts.jhmi.edu/es/dns.cfm

More information on DNS in general can be found here: http://www.internic.net/faqs/domain-names.html

Before beginning any Johns Hopkins Institutions web project, please contact the appropriate office in your area for assistance with guidelines, standards or existing programs. If there is any doubt about the methods for collecting, storing, or displaying sensitive information on web sites, the Johns Hopkins legal departments (410-516-8128) should be contacted for a definitive answer about Hopkins' liability and responsibility.