Currently, the majority of Internet Service Providers (ISPs) and websites continue to use IPv4 as the protocol for recognizing IP addresses. This is the typical IP address you will see throughout EZproxy documentation (eg. 123.456.789.101). However, as Internet use continues to grow, the potential for an exhaustion of all IPv4 addresses has become apparent, and IPv6 is the new protocol that all ISPs and websites will eventually use. In most places, IPv4 will continue to be the protocol recognized; however, if you live in certain regions or utilize resources based in these areas, such as Europe or Asia, you might find more and more IPv6 IP addresses attached to your resources or ISPs.
Adding the Option IPv6 directive to your config.txt file will ensure your continued access to resources as more and more IPv4 addresses are converted to IPv6 addresses. Adding this directive will still allow EZproxy to recognize and connect to resources with IPv4 addresses. Its addition to your config.txt makes EZproxy compatible with both IPv4 and IPv6 resources.
Option IPv6 is a position-independent config.txt directive that specifies the default network lookup order for DNS addresses. If this directive is specified, then the DNS lookup is performed for an IPv6 address. If that lookup fails, then an IPv4 lookup is performed.
If no Option IPv6 directive appears in config.txt, then lookups are only performed for IPv4 IP addresses. The Option IPv6 directive will perform DNS queries to IPv6 DNS servers based on directives that contain DNS names, such as URL, Host, or Domain statements. You do not need to alter these statements if you are using Option IPv6.
OCLC recommends placing this at the top off your config.txt with your Name, LoginPort, LoginPortSSL, and any other high level server directives and configuration.
Name ezproxy.abclib.org LoginPort 80 LoginSSL 443 Option IPv6
If you have an institution network with an IPv6 IP address or if you have traffic going over an IPv6 network, you can add this directive to your config.txt file so you can access these facilities.
Do not use this directive unless you are certain you have an IPv6 network. If you do not have any IPv6 networks and you include this directive, the DNS lookup will affect your server's performance.