diff --git a/checker/checker.go b/checker/checker.go
index d10787e..ddddaad 100644
--- a/checker/checker.go
+++ b/checker/checker.go
@@ -1,9 +1,11 @@
 package main
 
 import (
+	"errors"
 	"fmt"
 	"io/ioutil"
 	"log"
+	"net"
 	"net/http"
 	"time"
 
@@ -35,21 +37,73 @@ func check_ping(ip string, cb func(pkt *ping.Packet)) (err error) {
 
 // PORT 53
 
-func check_dns(domain, ip string) (err error) {
+func get_GLUE(domain string) (aaaa net.IP, err error) {
+	client := dns.Client{Net: "tcp", Timeout: time.Second * 5}
+
+	m := new(dns.Msg)
+	m.SetQuestion(domain, dns.TypeNS)
+	m.RecursionDesired = false
+	m.SetEdns0(4096, true)
+
+	var r *dns.Msg
+	r, _, err = client.Exchange(m, "[2a01:e0a:25a:9160::2]:53")
+	if err != nil {
+		return
+	}
+
+	if r == nil {
+		return nil, errors.New("response is nil")
+	}
+	if r.Rcode != dns.RcodeSuccess {
+		return nil, errors.New("failed to get a valid answer")
+	}
+
+	for _, extra := range r.Extra {
+		if t, ok := extra.(*dns.AAAA); ok {
+			aaaa = t.AAAA
+		}
+	}
+
+	return
+}
+
+func check_dns(domain, ip string) (aaaa net.IP, err error) {
 	client := dns.Client{Timeout: time.Second * 5}
 
 	m := new(dns.Msg)
-	m.SetQuestion(domain, dns.TypeSOA)
+	m.SetQuestion(domain, dns.TypeAAAA)
+
+	var r *dns.Msg
+	r, _, err = client.Exchange(m, fmt.Sprintf("[%s]:53", ip))
+	if err != nil {
+		return
+	}
+
+	if r == nil {
+		err = errors.New("response is nil")
+	}
+	if r.Rcode != dns.RcodeSuccess {
+		err = errors.New("failed to get a valid answer")
+	}
+
+	if len(r.Answer) > 0 {
+		aaaa = r.Answer[0].(*dns.AAAA).AAAA
+	}
 
-	_, _, err = client.Exchange(m, fmt.Sprintf("[%s]:53", ip))
 	return
 }
 
 // PORT 80
 
 func check_http(ip string) (err error) {
+	client := &http.Client{
+		CheckRedirect: func(req *http.Request, via []*http.Request) error {
+			return http.ErrUseLastResponse
+		},
+	}
+
 	var resp *http.Response
-	resp, err = http.Get(fmt.Sprintf("http://[%s]/", ip))
+	resp, err = client.Get(fmt.Sprintf("http://[%s]/", ip))
 	if err != nil {
 		return
 	}
@@ -118,32 +172,20 @@ func studentsChecker() {
 				return
 			}
 
-			// Check HTTP
-			if err := check_http(stdIP); err == nil {
-				if verbose {
-					log.Printf("%s just unlocked HTTP challenge\n", std.Login)
-				}
-				if _, err := std.UnlockNewChallenge(100*(tunnel_version-1)+0, ""); err != nil {
-					if _, err := std.UpdateUnlockedChallenge(100*(tunnel_version-1)+0, ""); err != nil {
-						log.Printf("Unable to register challenge for %s: %s\n", std.Login, err.Error())
-					}
-				}
-			}
+			dnsIP := stdIP
+			// Is GLUE defined?
+			if glueIP, err := get_GLUE(std.MyDelegatedDomain()); glueIP != nil {
+				dnsIP = glueIP.String()
 
-			// Check HTTPs
-			if err := check_https(std.MyAssociatedDomain(), stdIP); err == nil {
 				if verbose {
-					log.Printf("%s just unlocked HTTPS challenge\n", std.Login)
-				}
-				if _, err := std.UnlockNewChallenge(100*(tunnel_version-1)+1, ""); err != nil {
-					if _, err := std.UpdateUnlockedChallenge(100*(tunnel_version-1)+1, ""); err != nil {
-						log.Printf("Unable to register challenge for %s: %s\n", std.Login, err.Error())
-					}
+					log.Printf("%s has defined GLUE: %s\n", std.Login, dnsIP)
 				}
+			} else if err != nil {
+				log.Printf("%s and GLUE: %s\n", std.Login, err)
 			}
 
 			// Check DNS
-			if err := check_dns(std.MyDelegatedDomain(), stdIP); err == nil {
+			if addr, err := check_dns(std.MyDelegatedDomain(), dnsIP); err == nil {
 				if verbose {
 					log.Printf("%s just unlocked DNS challenge\n", std.Login)
 				}
@@ -152,6 +194,66 @@ func studentsChecker() {
 						log.Printf("Unable to register challenge for %s: %s\n", std.Login, err.Error())
 					}
 				}
+
+				// Check HTTP with DNS
+				if addr == nil {
+					log.Printf("%s and HTTP (with DNS ip=%s): skipped due to empty response\n", std.Login, addr.String())
+				} else if err := check_http(addr.String()); err == nil {
+					if verbose {
+						log.Printf("%s just unlocked HTTP challenge\n", std.Login)
+					}
+					if _, err := std.UnlockNewChallenge(100*(tunnel_version-1)+0, ""); err != nil {
+						if _, err := std.UpdateUnlockedChallenge(100*(tunnel_version-1)+0, ""); err != nil {
+							log.Printf("Unable to register challenge for %s: %s\n", std.Login, err.Error())
+						}
+					}
+				} else if verbose {
+					log.Printf("%s and HTTP (with DNS ip=%s): %s\n", std.Login, addr.String(), err)
+				}
+
+				// Check HTTPs with DNS
+				if addr == nil {
+					log.Printf("%s and HTTPS (with DNS ip=%s): skipped due to empty response\n", std.Login, addr.String())
+				} else if err := check_https(std.MyDelegatedDomain(), addr.String()); err == nil {
+					if verbose {
+						log.Printf("%s just unlocked HTTPS challenge\n", std.Login)
+					}
+					if _, err := std.UnlockNewChallenge(100*(tunnel_version-1)+1, ""); err != nil {
+						if _, err := std.UpdateUnlockedChallenge(100*(tunnel_version-1)+1, ""); err != nil {
+							log.Printf("Unable to register challenge for %s: %s\n", std.Login, err.Error())
+						}
+					}
+				} else if verbose {
+					log.Printf("%s and HTTPS (with DNS ip=%s): %s\n", std.Login, addr.String(), err)
+				}
+			} else {
+				// Check HTTP without DNS
+				if err := check_http(stdIP); err == nil {
+					if verbose {
+						log.Printf("%s just unlocked HTTP challenge\n", std.Login)
+					}
+					if _, err := std.UnlockNewChallenge(100*(tunnel_version-1)+0, ""); err != nil {
+						if _, err := std.UpdateUnlockedChallenge(100*(tunnel_version-1)+0, ""); err != nil {
+							log.Printf("Unable to register challenge for %s: %s\n", std.Login, err.Error())
+						}
+					}
+				} else if verbose {
+					log.Printf("%s and HTTP (without DNS): %s\n", std.Login, err)
+				}
+
+				// Check HTTPs without DNS
+				if err := check_https(std.MyAssociatedDomain(), stdIP); err == nil {
+					if verbose {
+						log.Printf("%s just unlocked HTTPS challenge\n", std.Login)
+					}
+					if _, err := std.UnlockNewChallenge(100*(tunnel_version-1)+1, ""); err != nil {
+						if _, err := std.UpdateUnlockedChallenge(100*(tunnel_version-1)+1, ""); err != nil {
+							log.Printf("Unable to register challenge for %s: %s\n", std.Login, err.Error())
+						}
+					}
+				} else if verbose {
+					log.Printf("%s and HTTPS (without DNS): %s\n", std.Login, err)
+				}
 			}
 
 			return